From 171ae8efee0b460e14d4561c678360348097dfca Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Tue, 25 Jun 2019 16:39:03 -0700
Subject: [PATCH 01/22] refactor to work with jupyter_server

---
 .../jupyter_server_config.d/voila.json        |   2 +-
 setup.py                                      |   2 +-
 .../default/nbconvert_templates/base.tpl      |  10 +-
 .../default/nbconvert_templates/voila.tpl     |   6 +-
 .../voila/templates/default/static/main.js    |   2 +-
 voila/__init__.py                             |   3 +-
 voila/app.py                                  | 374 +++---------------
 voila/handler.py                              |  34 +-
 voila/treehandler.py                          |   7 +-
 9 files changed, 86 insertions(+), 354 deletions(-)

diff --git a/etc/jupyter/jupyter_server_config.d/voila.json b/etc/jupyter/jupyter_server_config.d/voila.json
index ff38f42ff..7de60d1f5 100644
--- a/etc/jupyter/jupyter_server_config.d/voila.json
+++ b/etc/jupyter/jupyter_server_config.d/voila.json
@@ -1,7 +1,7 @@
 {
     "ServerApp": {
         "jpserver_extensions": {
-            "voila.server_extension": true
+            "voila": true
         }
     }
 }
diff --git a/setup.py b/setup.py
index 634ac7824..e615a1d95 100644
--- a/setup.py
+++ b/setup.py
@@ -371,7 +371,7 @@ def get_data_files():
     },
     'entry_points': {
         'console_scripts': [
-            'voila = voila.app:main'
+            'jupyter-voila = voila.app:main'
         ]
     },
     'install_requires': [
diff --git a/share/jupyter/voila/templates/default/nbconvert_templates/base.tpl b/share/jupyter/voila/templates/default/nbconvert_templates/base.tpl
index 386da08e8..7580b6801 100644
--- a/share/jupyter/voila/templates/default/nbconvert_templates/base.tpl
+++ b/share/jupyter/voila/templates/default/nbconvert_templates/base.tpl
@@ -14,11 +14,10 @@
 
 {%- block html_head_js -%}
 <script
-    src="{{resources.base_url}}voila/static/require.min.js"
+    src="{{resources.base_url}}static/voila/require.min.js"
     integrity="sha256-Ae2Vz/4ePdIu6ZyI/5ZGsYnb+m0JlOmKPjt6XZ9JJkA="
     crossorigin="anonymous">
 </script>
-
 {% block notebook_execute %}
     {%- set kernel_id = kernel_start() -%}
     <script id="jupyter-config-data" type="application/json">
@@ -50,10 +49,13 @@
 {% block footer %}
 {% block footer_js %}
 <script>
-requirejs.config({ baseUrl: '{{resources.base_url}}voila/', waitSeconds: 30})
+requirejs.config({
+    baseUrl: '{{resources.base_url}}static/voila/',
+    waitSeconds: 30
+})
 requirejs(
     [
-        "static/main",
+        "main",
     {% for ext in resources.nbextensions -%}
         "{{resources.base_url}}voila/nbextensions/{{ ext }}.js",
     {% endfor %}
diff --git a/share/jupyter/voila/templates/default/nbconvert_templates/voila.tpl b/share/jupyter/voila/templates/default/nbconvert_templates/voila.tpl
index f2d4ca648..e7f18bdb0 100644
--- a/share/jupyter/voila/templates/default/nbconvert_templates/voila.tpl
+++ b/share/jupyter/voila/templates/default/nbconvert_templates/voila.tpl
@@ -9,12 +9,12 @@
 {%- block html_head_css -%}
 {{ super() }}
 
-<link rel="stylesheet" type="text/css" href="{{resources.base_url}}voila/static/index.css">
+<link rel="stylesheet" type="text/css" href="{{resources.base_url}}static/voila/index.css"></link>
 
 {% if resources.theme == 'dark' %}
-    <link rel="stylesheet" type="text/css" href="{{resources.base_url}}voila/static/theme-dark.css">
+    <link rel="stylesheet" type="text/css" href="{{resources.base_url}}static/voila/theme-dark.css"></link>
 {% else %}
-    <link rel="stylesheet" type="text/css" href="{{resources.base_url}}voila/static/theme-light.css">
+    <link rel="stylesheet" type="text/css" href="{{resources.base_url}}static/voila/theme-light.css"></link>
 {% endif %}
 
 {% for css in resources.inlining.css %}
diff --git a/share/jupyter/voila/templates/default/static/main.js b/share/jupyter/voila/templates/default/static/main.js
index 99b6b4820..50597e9ee 100644
--- a/share/jupyter/voila/templates/default/static/main.js
+++ b/share/jupyter/voila/templates/default/static/main.js
@@ -7,7 +7,7 @@
 ****************************************************************************/
 
 // NOTE: this file is not transpiled, async/await is the only modern feature we use here
-require(['static/voila'], function(voila) {
+require(['voila'], function(voila) {
     // requirejs doesn't like to be passed an async function, so create one inside
     (async function() {
         var kernel = await voila.connectKernel()
diff --git a/voila/__init__.py b/voila/__init__.py
index 0cf9f3351..c9897f132 100644
--- a/voila/__init__.py
+++ b/voila/__init__.py
@@ -8,8 +8,9 @@
 #############################################################################
 
 from ._version import __version__  # noqa
-from .server_extension import load_jupyter_server_extension  # noqa
+from .app import Voila  # noqa
 
+load_jupyter_server_extension = Voila.load_jupyter_server_extension
 
 def _jupyter_nbextension_paths():
     return [dict(
diff --git a/voila/app.py b/voila/app.py
index a2ef8c7ec..9ea232f08 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -44,9 +44,7 @@
 from jupyter_server.utils import url_path_join
 from jupyter_server.services.config import ConfigManager
 from jupyter_server.base.handlers import FileFindHandler
-
-from jupyter_client.kernelspec import KernelSpecManager
-
+from jupyter_server.extension.application import ExtensionApp
 from jupyter_core.paths import jupyter_config_path, jupyter_path
 
 from ipython_genutils.py3compat import getcwd
@@ -55,8 +53,6 @@
 from .handler import VoilaHandler
 from .treehandler import VoilaTreeHandler
 from ._version import __version__
-from .static_file_handler import MultiStaticFileHandler, WhiteListFileHandler
-from .configuration import VoilaConfiguration
 from .execute import VoilaExecutePreprocessor
 from .exporter import VoilaExporter
 from .csspreprocessor import VoilaCSSPreprocessor
@@ -69,10 +65,12 @@ def _(x):
     return x
 
 
-class Voila(Application):
+class Voila(ExtensionApp):
     name = 'voila'
     version = __version__
     examples = 'voila example.ipynb --port 8888'
+    
+    extension_name = 'voila'
 
     flags = {
         'debug': ({'Voila': {'log_level': logging.DEBUG}}, _("Set the log level to logging.DEBUG")),
@@ -92,13 +90,7 @@ class Voila(Application):
         """
     )
     notebook_filename = Unicode()
-    port = Integer(
-        8866,
-        config=True,
-        help=_(
-            'Port of the voila server. Default 8866.'
-        )
-    )
+
     autoreload = Bool(
         False,
         config=True,
@@ -126,11 +118,23 @@ class Voila(Application):
         'enable_nbextensions': 'VoilaConfiguration.enable_nbextensions'
     }
     classes = [
-        VoilaConfiguration,
         VoilaExecutePreprocessor,
         VoilaExporter,
         VoilaCSSPreprocessor
     ]
+
+    template = Unicode(
+        'default',
+        config=True,
+        allow_none=True,
+        help=(
+            'template name to be used by voila.'
+        )
+    )
+    theme = Unicode('light').tag(config=True)
+    strip_sources = Bool(True, help='Strip sources from rendered html').tag(config=True)
+    enable_nbextensions = Bool(False, config=True, help=('Set to True for Voila to load notebook extensions'))
+
     connection_dir_root = Unicode(
         config=True,
         help=_(
@@ -195,29 +199,6 @@ class Voila(Application):
         )
     )
 
-    port_retries = Integer(50, config=True,
-                           help=_("The number of additional ports to try if the specified port is not available.")
-                           )
-
-    ip = Unicode('localhost', config=True,
-                 help=_("The IP address the notebook server will listen on."))
-
-    open_browser = Bool(True, config=True,
-                        help=_("""Whether to open in a browser after starting.
-                        The specific browser used is platform dependent and
-                        determined by the python standard library `webbrowser`
-                        module, unless it is overridden using the --browser
-                        (NotebookApp.browser) configuration option.
-                        """))
-
-    browser = Unicode(u'', config=True,
-                      help="""Specify what command to use to invoke a web
-                      browser when opening the notebook. If not specified, the
-                      default browser will be determined by the `webbrowser`
-                      standard library module, which allows setting of the
-                      BROWSER environment variable to override it.
-                      """)
-
     webbrowser_open_new = Integer(2, config=True,
                                   help=_("""Specify Where to open the notebook on startup. This is the
                                   `new` argument passed to the standard library method `webbrowser.open`.
@@ -239,38 +220,6 @@ class Voila(Application):
                                  cannot be determined reliably by the Jupyter notebook server (proxified
                                  or containerized setups for example)."""))
 
-    @property
-    def display_url(self):
-        if self.custom_display_url:
-            url = self.custom_display_url
-            if not url.endswith('/'):
-                url += '/'
-        else:
-            if self.ip in ('', '0.0.0.0'):
-                ip = "%s" % socket.gethostname()
-            else:
-                ip = self.ip
-            url = self._url(ip)
-        # TODO: do we want to have the token?
-        # if self.token:
-        #     # Don't log full token if it came from config
-        #     token = self.token if self._token_generated else '...'
-        #     url = (url_concat(url, {'token': token})
-        #           + '\n or '
-        #           + url_concat(self._url('127.0.0.1'), {'token': token}))
-        return url
-
-    @property
-    def connection_url(self):
-        ip = self.ip if self.ip else 'localhost'
-        return self._url(ip)
-
-    def _url(self, ip):
-        # TODO: https / certfile
-        # proto = 'https' if self.certfile else 'http'
-        proto = 'http'
-        return "%s://%s:%i%s" % (proto, ip, self.port, self.base_url)
-
     config_file_paths = List(
         Unicode(),
         config=True,
@@ -279,28 +228,10 @@ def _url(self, ip):
         )
     )
 
-    tornado_settings = Dict(
-        {},
-        config=True,
-        help=_(
-            'Extra settings to apply to tornado application, e.g. headers, ssl, etc'
-        )
-    )
-
     @default('config_file_paths')
     def _config_file_paths_default(self):
         return [os.getcwd()] + jupyter_config_path()
 
-    @default('connection_dir_root')
-    def _default_connection_dir(self):
-        connection_dir = tempfile.gettempdir()
-        self.log.info('Using %s to store connection files' % connection_dir)
-        return connection_dir
-
-    @default('log_level')
-    def _default_log_level(self):
-        return logging.INFO
-
     # similar to NotebookApp, except no extra path
     @property
     def nbextensions_path(self):
@@ -322,251 +253,46 @@ def _default_root_dir(self):
         else:
             return getcwd()
 
-    def initialize(self, argv=None):
-        self.log.debug("Searching path %s for config files", self.config_file_paths)
-        # to make config_file_paths settable via cmd line, we first need to parse it
-        super(Voila, self).initialize(argv)
-        if len(self.extra_args) == 1:
-            arg = self.extra_args[0]
-            # I am not sure why we need to check if self.notebook_path is set, can we get rid of this?
-            if not self.notebook_path:
-                if os.path.isdir(arg):
-                    self.root_dir = arg
-                elif os.path.isfile(arg):
-                    self.notebook_path = arg
-                else:
-                    raise ValueError('argument is neither a file nor a directory: %r' % arg)
-        elif len(self.extra_args) != 0:
-            raise ValueError('provided more than 1 argument: %r' % self.extra_args)
-
-        # then we load the config
-        self.load_config_file('voila', path=self.config_file_paths)
-        # but that cli config has preference, so we overwrite with that
-        self.update_config(self.cli_config)
-        # common configuration options between the server extension and the application
-        self.voila_configuration = VoilaConfiguration(parent=self)
-        self.setup_template_dirs()
-        signal.signal(signal.SIGTERM, self._handle_signal_stop)
-
-    def setup_template_dirs(self):
-        if self.voila_configuration.template:
-            collect_template_paths(
-                self.nbconvert_template_paths,
-                self.static_paths,
-                self.template_paths,
-                self.voila_configuration.template)
-        self.log.debug('using template: %s', self.voila_configuration.template)
-        self.log.debug('nbconvert template paths:\n\t%s', '\n\t'.join(self.nbconvert_template_paths))
-        self.log.debug('template paths:\n\t%s', '\n\t'.join(self.template_paths))
-        self.log.debug('static paths:\n\t%s', '\n\t'.join(self.static_paths))
-        if self.notebook_path and not os.path.exists(self.notebook_path):
-            raise ValueError('Notebook not found: %s' % self.notebook_path)
-
-    def _handle_signal_stop(self, sig, frame):
-        self.log.info('Handle signal %s.' % sig)
-        self.ioloop.add_callback_from_signal(self.ioloop.stop)
-
-    def start(self):
-        self.connection_dir = tempfile.mkdtemp(
-            prefix='voila_',
-            dir=self.connection_dir_root
-        )
-        self.log.info('Storing connection files in %s.' % self.connection_dir)
-        self.log.info('Serving static files from %s.' % self.static_root)
 
-        self.kernel_spec_manager = KernelSpecManager(
-            parent=self
-        )
+    default_url = Unicode("/voila", config=True)
 
-        self.kernel_manager = MappingKernelManager(
-            parent=self,
-            connection_dir=self.connection_dir,
-            kernel_spec_manager=self.kernel_spec_manager,
-            allowed_message_types=[
-                'comm_msg',
-                'comm_info_request',
-                'kernel_info_request',
-                'shutdown_request'
-            ]
+    def initialize_templates(self):
+        # common configuration options between the server extension and the application
+        collect_template_paths(
+            self.nbconvert_template_paths,
+            self.static_paths,
+            self.template_paths,
+            self.template
         )
-
-        jenv_opt = {"autoescape": True}  # we might want extra options via cmd line like notebook server
+        jenv_opt = {"autoescape": True}
         env = jinja2.Environment(loader=jinja2.FileSystemLoader(self.template_paths), extensions=['jinja2.ext.i18n'], **jenv_opt)
+
         nbui = gettext.translation('nbui', localedir=os.path.join(ROOT, 'i18n'), fallback=True)
         env.install_gettext_translations(nbui, newstyle=False)
-        self.contents_manager = LargeFileManager(parent=self)
-
-        # we create a config manager that load both the serverconfig and nbconfig (classical notebook)
-        read_config_path = [os.path.join(p, 'serverconfig') for p in jupyter_config_path()]
-        read_config_path += [os.path.join(p, 'nbconfig') for p in jupyter_config_path()]
-        self.config_manager = ConfigManager(parent=self, read_config_path=read_config_path)
-
-        # default server_url to base_url
-        self.server_url = self.server_url or self.base_url
-
-        self.app = tornado.web.Application(
-            base_url=self.base_url,
-            server_url=self.server_url or self.base_url,
-            kernel_manager=self.kernel_manager,
-            kernel_spec_manager=self.kernel_spec_manager,
-            allow_remote_access=True,
-            autoreload=self.autoreload,
+
+        template_settings = dict(
+            voila_template_paths=self.template_paths,
             voila_jinja2_env=env,
-            jinja2_env=env,
-            static_path='/',
-            server_root_dir='/',
-            contents_manager=self.contents_manager,
-            config_manager=self.config_manager
+            nbconvert_template_paths=self.nbconvert_template_paths
         )
-
-        self.app.settings.update(self.tornado_settings)
-
-        handlers = []
-
-        handlers.extend([
-            (url_path_join(self.server_url, r'/api/kernels/%s' % _kernel_id_regex), KernelHandler),
-            (url_path_join(self.server_url, r'/api/kernels/%s/channels' % _kernel_id_regex), ZMQChannelsHandler),
-            (
-                url_path_join(self.server_url, r'/voila/static/(.*)'),
-                MultiStaticFileHandler,
-                {
-                    'paths': self.static_paths,
-                    'default_filename': 'index.html'
-                }
-            )
-        ])
-
-        # Serving notebook extensions
-        if self.voila_configuration.enable_nbextensions:
-            handlers.append(
-                (
-                    url_path_join(self.server_url, r'/voila/nbextensions/(.*)'),
-                    FileFindHandler,
-                    {
-                        'path': self.nbextensions_path,
-                        'no_cache_paths': ['/'],  # don't cache anything in nbextensions
-                    },
-                )
-            )
-        handlers.append(
-            (
-                url_path_join(self.server_url, r'/voila/files/(.*)'),
-                WhiteListFileHandler,
-                {
-                    'whitelist': self.voila_configuration.file_whitelist,
-                    'blacklist': self.voila_configuration.file_blacklist,
-                    'path': self.root_dir,
-                },
-            )
+        self.settings.update(**template_settings)
+
+    def initialize_settings(self):
+        voila_configuration = dict(
+            template=self.template,
+            theme=self.theme,
+            strip_sources=self.strip_sources,
+            enable_nbextensions=self.enable_nbextensions,
+            notebook_path=self.notebook_path,
         )
-
-        tree_handler_conf = {
-            'voila_configuration': self.voila_configuration
-        }
-        if self.notebook_path:
-            handlers.append((
-                url_path_join(self.server_url, r'/(.*)'),
-                VoilaHandler,
-                {
-                    'notebook_path': os.path.relpath(self.notebook_path, self.root_dir),
-                    'nbconvert_template_paths': self.nbconvert_template_paths,
-                    'config': self.config,
-                    'voila_configuration': self.voila_configuration
-                }
-            ))
-        else:
-            self.log.debug('serving directory: %r', self.root_dir)
-            handlers.extend([
-                (self.server_url, VoilaTreeHandler, tree_handler_conf),
-                (url_path_join(self.server_url, r'/voila/tree' + path_regex), VoilaTreeHandler, tree_handler_conf),
-                (url_path_join(self.server_url, r'/voila/render/(.*)'), VoilaHandler,
-                    {
-                        'nbconvert_template_paths': self.nbconvert_template_paths,
-                        'config': self.config,
-                        'voila_configuration': self.voila_configuration
-                    }),
-            ])
-
-        self.app.add_handlers('.*$', handlers)
-        self.listen()
-
-    def stop(self):
-        shutil.rmtree(self.connection_dir)
-        self.kernel_manager.shutdown_all()
-
-    def random_ports(self, port, n):
-        """Generate a list of n random ports near the given port.
-
-        The first 5 ports will be sequential, and the remaining n-5 will be
-        randomly selected in the range [port-2*n, port+2*n].
-        """
-        for i in range(min(5, n)):
-            yield port + i
-        for i in range(n-5):
-            yield max(1, port + random.randint(-2*n, 2*n))
-
-    def listen(self):
-        for port in self.random_ports(self.port, self.port_retries+1):
-            try:
-                self.app.listen(port)
-                self.port = port
-                self.log.info('Voila is running at:\n%s' % self.display_url)
-            except socket.error as e:
-                if e.errno == errno.EADDRINUSE:
-                    self.log.info(_('The port %i is already in use, trying another port.') % port)
-                    continue
-                elif e.errno in (errno.EACCES, getattr(errno, 'WSAEACCES', errno.EACCES)):
-                    self.log.warning(_("Permission to listen on port %i denied") % port)
-                    continue
-                else:
-                    raise
-            else:
-                self.port = port
-                success = True
-                break
-
-        if not success:
-            self.log.critical(_('ERROR: the voila server could not be started because '
-                              'no available port could be found.'))
-            self.exit(1)
-
-        if self.open_browser:
-            self.launch_browser()
-
-        self.ioloop = tornado.ioloop.IOLoop.current()
-        try:
-            self.ioloop.start()
-        except KeyboardInterrupt:
-            self.log.info('Stopping...')
-        finally:
-            self.stop()
-
-    def launch_browser(self):
-        try:
-            browser = webbrowser.get(self.browser or None)
-        except webbrowser.Error as e:
-            self.log.warning(_('No web browser found: %s.') % e)
-            browser = None
-
-        if not browser:
-            return
-
-        uri = self.base_url
-        fd, open_file = tempfile.mkstemp(suffix='.html')
-        # Write a temporary file to open in the browser
-        with io.open(fd, 'w', encoding='utf-8') as fh:
-            # TODO: do we want to have the token?
-            # if self.token:
-            #     url = url_concat(url, {'token': self.token})
-            url = url_path_join(self.connection_url, uri)
-
-            jinja2_env = self.app.settings['jinja2_env']
-            template = jinja2_env.get_template('browser-open.html')
-            fh.write(template.render(open_url=url, base_url=url))
-
-        def target():
-            return browser.open(urljoin('file:', pathname2url(open_file)), new=self.webbrowser_open_new)
-        threading.Thread(target=target).start()
-
+        self.settings['voila_configuration'] = voila_configuration
+
+    def initialize_handlers(self):
+        handlers = [
+            ('/voila/render' + path_regex, VoilaHandler),
+            ('/voila', VoilaTreeHandler),
+            ('/voila/tree' + path_regex, VoilaTreeHandler),
+        ]
+        self.handlers.extend(handlers)
 
 main = Voila.launch_instance
diff --git a/voila/handler.py b/voila/handler.py
index 92d0a59e8..3500e5d56 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -11,10 +11,7 @@
 
 import tornado.web
 
-from jupyter_server.base.handlers import JupyterHandler
-from jupyter_server.config_manager import recursive_update
-from jupyter_server.utils import url_path_join
-import nbformat
+from jupyter_server.extension.handler import ExtensionHandler
 
 from nbconvert.preprocessors import ClearOutputPreprocessor
 
@@ -31,15 +28,24 @@ def filter_empty_code_cells(cell, exporter):
     )
 
 
-class VoilaHandler(JupyterHandler):
+class VoilaHandler(ExtensionHandler):
+    
+    @property
+    def notebook_path(self):
+        return self.settings.get('notebook_path', [])
+
+    @property
+    def nbconvert_template_paths(self):
+        return self.settings.get('nbconvert_template_paths', [])
+
+    @property
+    def exporter_config(self):
+        return self.settings.get('config', None)
+
+    @property
+    def voila_configuration(self):
+        return self.settings['voila_configuration']
 
-    def initialize(self, **kwargs):
-        self.notebook_path = kwargs.pop('notebook_path', [])    # should it be []
-        self.nbconvert_template_paths = kwargs.pop('nbconvert_template_paths', [])
-        self.traitlet_config = kwargs.pop('config', None)
-        self.voila_configuration = kwargs['voila_configuration']
-        # we want to avoid starting multiple kernels due to template mistakes
-        self.kernel_started = False
 
     @tornado.web.authenticated
     @tornado.gen.coroutine
@@ -50,7 +56,7 @@ def get(self, path=None):
             self.redirect_to_file(path)
             return
 
-        if self.voila_configuration.enable_nbextensions:
+        if self.voila_configuration['enable_nbextensions']:
             # generate a list of nbextensions that are enabled for the classical notebook
             # a template can use that to load classical notebook extensions, but does not have to
             notebook_config = self.config_manager.get('notebook')
@@ -73,7 +79,7 @@ def get(self, path=None):
         resources = {
             'base_url': self.base_url,
             'nbextensions': nbextensions,
-            'theme': self.voila_configuration.theme
+            'theme': self.voila_configuration['theme']
         }
 
         # include potential extra resources
diff --git a/voila/treehandler.py b/voila/treehandler.py
index f6d791319..1ee6ac59c 100644
--- a/voila/treehandler.py
+++ b/voila/treehandler.py
@@ -10,16 +10,13 @@
 
 from tornado import web
 
-from jupyter_server.base.handlers import JupyterHandler
+from jupyter_server.extension.handler import ExtensionHandler
 from jupyter_server.utils import url_path_join, url_escape
 
 from .utils import get_server_root_dir
 
 
-class VoilaTreeHandler(JupyterHandler):
-    def initialize(self, **kwargs):
-        self.voila_configuration = kwargs['voila_configuration']
-        self.allowed_extensions = list(self.voila_configuration.extension_language_mapping.keys()) + ['.ipynb']
+class VoilaTreeHandler(ExtensionHandler):
 
     def get_template(self, name):
         """Return the jinja template object for a given name"""

From 2d9f1c6c4d85d59a335faca295d79ef31b3393ef Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Mon, 1 Jul 2019 13:17:26 -0700
Subject: [PATCH 02/22] simplify handling of config

---
 voila/app.py                 | 63 ++++++++++--------------------------
 voila/handler.py             | 37 ++++++++-------------
 voila/static_file_handler.py |  2 +-
 3 files changed, 31 insertions(+), 71 deletions(-)

diff --git a/voila/app.py b/voila/app.py
index 9ea232f08..5968d35e3 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -68,13 +68,13 @@ def _(x):
 class Voila(ExtensionApp):
     name = 'voila'
     version = __version__
-    examples = 'voila example.ipynb --port 8888'
-    
+    examples = 'jupyter voila example.ipynb'
     extension_name = 'voila'
 
     flags = {
         'debug': ({'Voila': {'log_level': logging.DEBUG}}, _("Set the log level to logging.DEBUG")),
-        'no-browser': ({'Voila': {'open_browser': False}}, _('Don\'t open the notebook in a browser after startup.'))
+        'no-browser': ({'Voila': {'open_browser': False}}, _('Don\'t open the notebook in a browser after startup.')),
+        'standalone': ({'ServerApp': {'standalone': True}}, _('Run the server without enabling extensions.'))
     }
 
     description = Unicode(
@@ -107,15 +107,13 @@ class Voila(ExtensionApp):
         )
     )
     aliases = {
-        'port': 'Voila.port',
+        'port': 'ServerApp.port',
         'static': 'Voila.static_root',
-        'strip_sources': 'VoilaConfiguration.strip_sources',
+        'strip_sources': 'Voila.strip_sources',
         'autoreload': 'Voila.autoreload',
-        'template': 'VoilaConfiguration.template',
-        'theme': 'VoilaConfiguration.theme',
-        'base_url': 'Voila.base_url',
-        'server_url': 'Voila.server_url',
-        'enable_nbextensions': 'VoilaConfiguration.enable_nbextensions'
+        'template': 'Voila.template',
+        'theme': 'Voila.theme',
+        'enable_nbextensions': 'Voila.enable_nbextensions',
     }
     classes = [
         VoilaExecutePreprocessor,
@@ -131,6 +129,14 @@ class Voila(ExtensionApp):
             'template name to be used by voila.'
         )
     )
+    resources = Dict(
+        allow_none=True,
+        help="""
+        extra resources used by templates;
+        example use with --template=reveal
+        --VoilaConfiguration.resources="{'reveal': {'transition': 'fade', 'scroll': True}}"
+        """
+    ).tag(config=True)
     theme = Unicode('light').tag(config=True)
     strip_sources = Bool(True, help='Strip sources from rendered html').tag(config=True)
     enable_nbextensions = Bool(False, config=True, help=('Set to True for Voila to load notebook extensions'))
@@ -144,27 +150,6 @@ class Voila(ExtensionApp):
     )
     connection_dir = Unicode()
 
-    base_url = Unicode(
-        '/',
-        config=True,
-        help=_(
-            'Path for voila API calls. If server_url is unset, this will be \
-            used for both the base route of the server and the client. \
-            If server_url is set, the server will server the routes prefixed \
-            by server_url, while the client will prefix by base_url (this is \
-            useful in reverse proxies).'
-        )
-    )
-
-    server_url = Unicode(
-        None,
-        config=True,
-        allow_none=True,
-        help=_(
-            'Path to prefix to voila API handlers. Leave unset to default to base_url'
-        )
-    )
-
     notebook_path = Unicode(
         None,
         config=True,
@@ -270,23 +255,9 @@ def initialize_templates(self):
         nbui = gettext.translation('nbui', localedir=os.path.join(ROOT, 'i18n'), fallback=True)
         env.install_gettext_translations(nbui, newstyle=False)
 
-        template_settings = dict(
-            voila_template_paths=self.template_paths,
-            voila_jinja2_env=env,
-            nbconvert_template_paths=self.nbconvert_template_paths
-        )
+        template_settings = {'voila_jinja2_env': env}
         self.settings.update(**template_settings)
 
-    def initialize_settings(self):
-        voila_configuration = dict(
-            template=self.template,
-            theme=self.theme,
-            strip_sources=self.strip_sources,
-            enable_nbextensions=self.enable_nbextensions,
-            notebook_path=self.notebook_path,
-        )
-        self.settings['voila_configuration'] = voila_configuration
-
     def initialize_handlers(self):
         handlers = [
             ('/voila/render' + path_regex, VoilaHandler),
diff --git a/voila/handler.py b/voila/handler.py
index 3500e5d56..e18c03b43 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -12,8 +12,9 @@
 import tornado.web
 
 from jupyter_server.extension.handler import ExtensionHandler
-
+from jupyter_server.config_manager import recursive_update
 from nbconvert.preprocessors import ClearOutputPreprocessor
+import nbformat
 
 from .execute import executenb, VoilaExecutePreprocessor
 from .exporter import VoilaExporter
@@ -29,23 +30,6 @@ def filter_empty_code_cells(cell, exporter):
 
 
 class VoilaHandler(ExtensionHandler):
-    
-    @property
-    def notebook_path(self):
-        return self.settings.get('notebook_path', [])
-
-    @property
-    def nbconvert_template_paths(self):
-        return self.settings.get('nbconvert_template_paths', [])
-
-    @property
-    def exporter_config(self):
-        return self.settings.get('config', None)
-
-    @property
-    def voila_configuration(self):
-        return self.settings['voila_configuration']
-
 
     @tornado.web.authenticated
     @tornado.gen.coroutine
@@ -56,7 +40,7 @@ def get(self, path=None):
             self.redirect_to_file(path)
             return
 
-        if self.voila_configuration['enable_nbextensions']:
+        if self.config.enable_nbextensions:
             # generate a list of nbextensions that are enabled for the classical notebook
             # a template can use that to load classical notebook extensions, but does not have to
             notebook_config = self.config_manager.get('notebook')
@@ -75,24 +59,29 @@ def get(self, path=None):
             return
         self.cwd = os.path.dirname(notebook_path)
 
+        # Launch kernel and execute notebook
+        kernel_id = yield tornado.gen.maybe_future(self.kernel_manager.start_kernel(kernel_name=notebook.metadata.kernelspec.name, path=self.cwd))
+        km = self.kernel_manager.get_kernel(kernel_id)
+        result = executenb(notebook, km=km, cwd=self.cwd, config=self.server_config)
+
         # render notebook to html
         resources = {
             'base_url': self.base_url,
             'nbextensions': nbextensions,
-            'theme': self.voila_configuration['theme']
+            'theme': self.config.theme
         }
 
         # include potential extra resources
-        extra_resources = self.voila_configuration.resources
+        extra_resources = self.config.resources
         if extra_resources:
             recursive_update(resources, extra_resources)
 
         self.exporter = VoilaExporter(
-            template_path=self.nbconvert_template_paths,
-            config=self.traitlet_config,
+            template_path=self.config.nbconvert_template_paths,
+            config=self.server_config,
             contents_manager=self.contents_manager  # for the image inlining
         )
-        if self.voila_configuration.strip_sources:
+        if self.config.strip_sources:
             self.exporter.exclude_input = True
             self.exporter.exclude_output_prompt = True
             self.exporter.exclude_input_prompt = True
diff --git a/voila/static_file_handler.py b/voila/static_file_handler.py
index 76eb6729b..fe0293942 100644
--- a/voila/static_file_handler.py
+++ b/voila/static_file_handler.py
@@ -33,7 +33,7 @@ def initialize(self, paths, default_filename=None):
     def get_absolute_path(self, root, path):
         # find the first absolute path that exists
         self.root = self.roots[0]
-        for root in self.roots:
+        for root in self.roots:git 
             abspath = os.path.abspath(os.path.join(root, path))
             if os.path.exists(abspath):
                 self.root = root  # make sure all the other methods in the base class know how to find the file

From 437d8ff75ee830e00511c90984678edd972dc952 Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Fri, 23 Aug 2019 16:02:15 -0700
Subject: [PATCH 03/22] fix tests/app/config_paths_test

---
 js/package-lock.json             | 41 +++++++++-----------------------
 tests/app/config_paths_test.py   | 18 ++++----------
 tests/app/conftest.py            | 14 ++++-------
 tests/configs/general/voila.json |  8 +------
 voila/app.py                     |  3 +++
 voila/handler.py                 |  4 ++++
 6 files changed, 28 insertions(+), 60 deletions(-)

diff --git a/js/package-lock.json b/js/package-lock.json
index 55ee11b98..81c1fdb7b 100644
--- a/js/package-lock.json
+++ b/js/package-lock.json
@@ -4875,8 +4875,7 @@
           "version": "2.1.1",
           "resolved": "https://registry.npmjs.org/ansi-regex/-/ansi-regex-2.1.1.tgz",
           "integrity": "sha1-w7M6te42DYbg5ijwRorn7yfWVN8=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "aproba": {
           "version": "1.2.0",
@@ -4900,15 +4899,13 @@
           "version": "1.0.0",
           "resolved": "https://registry.npmjs.org/balanced-match/-/balanced-match-1.0.0.tgz",
           "integrity": "sha1-ibTRmasr7kneFk6gK4nORi1xt2c=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "brace-expansion": {
           "version": "1.1.11",
           "resolved": "https://registry.npmjs.org/brace-expansion/-/brace-expansion-1.1.11.tgz",
           "integrity": "sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==",
           "dev": true,
-          "optional": true,
           "requires": {
             "balanced-match": "^1.0.0",
             "concat-map": "0.0.1"
@@ -4925,22 +4922,19 @@
           "version": "1.1.0",
           "resolved": "https://registry.npmjs.org/code-point-at/-/code-point-at-1.1.0.tgz",
           "integrity": "sha1-DQcLTQQ6W+ozovGkDi7bPZpMz3c=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "concat-map": {
           "version": "0.0.1",
           "resolved": "https://registry.npmjs.org/concat-map/-/concat-map-0.0.1.tgz",
           "integrity": "sha1-2Klr13/Wjfd5OnMDajug1UBdR3s=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "console-control-strings": {
           "version": "1.1.0",
           "resolved": "https://registry.npmjs.org/console-control-strings/-/console-control-strings-1.1.0.tgz",
           "integrity": "sha1-PXz0Rk22RG6mRL9LOVB/mFEAjo4=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "core-util-is": {
           "version": "1.0.2",
@@ -5071,8 +5065,7 @@
           "version": "2.0.3",
           "resolved": "https://registry.npmjs.org/inherits/-/inherits-2.0.3.tgz",
           "integrity": "sha1-Yzwsg+PaQqUC9SRmAiSA9CCCYd4=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "ini": {
           "version": "1.3.5",
@@ -5086,7 +5079,6 @@
           "resolved": "https://registry.npmjs.org/is-fullwidth-code-point/-/is-fullwidth-code-point-1.0.0.tgz",
           "integrity": "sha1-754xOG8DGn8NZDr4L95QxFfvAMs=",
           "dev": true,
-          "optional": true,
           "requires": {
             "number-is-nan": "^1.0.0"
           }
@@ -5103,7 +5095,6 @@
           "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-3.0.4.tgz",
           "integrity": "sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==",
           "dev": true,
-          "optional": true,
           "requires": {
             "brace-expansion": "^1.1.7"
           }
@@ -5112,15 +5103,13 @@
           "version": "0.0.8",
           "resolved": "https://registry.npmjs.org/minimist/-/minimist-0.0.8.tgz",
           "integrity": "sha1-hX/Kv8M5fSYluCKCYuhqp6ARsF0=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "minipass": {
           "version": "2.3.5",
           "resolved": "https://registry.npmjs.org/minipass/-/minipass-2.3.5.tgz",
           "integrity": "sha512-Gi1W4k059gyRbyVUZQ4mEqLm0YIUiGYfvxhF6SIlk3ui1WVxMTGfGdQ2SInh3PDrRTVvPKgULkpJtT4RH10+VA==",
           "dev": true,
-          "optional": true,
           "requires": {
             "safe-buffer": "^5.1.2",
             "yallist": "^3.0.0"
@@ -5141,7 +5130,6 @@
           "resolved": "https://registry.npmjs.org/mkdirp/-/mkdirp-0.5.1.tgz",
           "integrity": "sha1-MAV0OOrGz3+MR2fzhkjWaX11yQM=",
           "dev": true,
-          "optional": true,
           "requires": {
             "minimist": "0.0.8"
           }
@@ -5230,8 +5218,7 @@
           "version": "1.0.1",
           "resolved": "https://registry.npmjs.org/number-is-nan/-/number-is-nan-1.0.1.tgz",
           "integrity": "sha1-CXtgK1NCKlIsGvuHkDGDNpQaAR0=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "object-assign": {
           "version": "4.1.1",
@@ -5245,7 +5232,6 @@
           "resolved": "https://registry.npmjs.org/once/-/once-1.4.0.tgz",
           "integrity": "sha1-WDsap3WWHUsROsF9nFC6753Xa9E=",
           "dev": true,
-          "optional": true,
           "requires": {
             "wrappy": "1"
           }
@@ -5341,8 +5327,7 @@
           "version": "5.1.2",
           "resolved": "https://registry.npmjs.org/safe-buffer/-/safe-buffer-5.1.2.tgz",
           "integrity": "sha512-Gd2UZBJDkXlY7GbJxfsE8/nvKkUEU1G38c1siN6QP6a9PT9MmHB8GnpscSmMJSoF8LOIrt8ud/wPtojys4G6+g==",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "safer-buffer": {
           "version": "2.1.2",
@@ -5384,7 +5369,6 @@
           "resolved": "https://registry.npmjs.org/string-width/-/string-width-1.0.2.tgz",
           "integrity": "sha1-EYvfW4zcUaKn5w0hHgfisLmxB9M=",
           "dev": true,
-          "optional": true,
           "requires": {
             "code-point-at": "^1.0.0",
             "is-fullwidth-code-point": "^1.0.0",
@@ -5406,7 +5390,6 @@
           "resolved": "https://registry.npmjs.org/strip-ansi/-/strip-ansi-3.0.1.tgz",
           "integrity": "sha1-ajhfuIU9lS1f8F0Oiq+UJ43GPc8=",
           "dev": true,
-          "optional": true,
           "requires": {
             "ansi-regex": "^2.0.0"
           }
@@ -5455,15 +5438,13 @@
           "version": "1.0.2",
           "resolved": "https://registry.npmjs.org/wrappy/-/wrappy-1.0.2.tgz",
           "integrity": "sha1-tSQ9jz7BqjXxNkYFvA0QNuMKtp8=",
-          "dev": true,
-          "optional": true
+          "dev": true
         },
         "yallist": {
           "version": "3.0.3",
           "resolved": "https://registry.npmjs.org/yallist/-/yallist-3.0.3.tgz",
           "integrity": "sha512-S+Zk8DEWE6oKpV+vI3qWkaK+jSbIK86pCwe2IF/xwIpQ8jEuxpw9NyaGjmp9+BoJv5FV2piqCDcoCtStppiq2A==",
-          "dev": true,
-          "optional": true
+          "dev": true
         }
       }
     },
diff --git a/tests/app/config_paths_test.py b/tests/app/config_paths_test.py
index aceed7fc9..945831843 100644
--- a/tests/app/config_paths_test.py
+++ b/tests/app/config_paths_test.py
@@ -9,22 +9,12 @@
 
 @pytest.fixture
 def voila_config_file_paths_arg():
-    path = os.path.join(BASE_DIR, '..', 'configs', 'general')
-    return '--VoilaTest.config_file_paths=[%r]' % path
-
+    config_path = os.path.join(BASE_DIR, '..', 'configs', 'general')
+    return '--VoilaTest.config_file_paths=[%r]' % config_path
 
 def test_config_app(voila_app):
-    assert voila_app.voila_configuration.template == 'test_template'
-    assert voila_app.voila_configuration.enable_nbextensions is True
-
-
-def test_config_kernel_manager(voila_app):
-    assert voila_app.kernel_manager.cull_interval == 10
-
-
-def test_config_contents_manager(voila_app):
-    assert voila_app.contents_manager.use_atomic_writing is False
-
+    assert voila_app.template == 'test_template'
+    assert voila_app.enable_nbextensions is True
 
 @pytest.mark.gen_test
 def test_template(http_client, base_url):
diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 08d1e4e5c..276f957c7 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -36,15 +36,11 @@ def voila_args(voila_notebook, voila_args_extra, voila_config_file_paths_arg):
 
 @pytest.fixture
 def voila_app(voila_args, voila_config):
-    voila_app = VoilaTest.instance()
-    voila_app.initialize(voila_args + ['--no-browser'])
+    server_app = VoilaTest.initialize_server(argv=['--ServerApp.open_browser=False'])
+    voila_app = VoilaTest._prepare_launch(server_app, argv=voila_args)
     voila_config(voila_app)
-    voila_app.start()
+    voila_app.start_server()
     yield voila_app
-    voila_app.stop()
+    server_app.stop()
+    server_app.clear_instance()
     voila_app.clear_instance()
-
-
-@pytest.fixture
-def app(voila_app):
-    return voila_app.app
diff --git a/tests/configs/general/voila.json b/tests/configs/general/voila.json
index 2ff5508c3..ef512000f 100644
--- a/tests/configs/general/voila.json
+++ b/tests/configs/general/voila.json
@@ -1,12 +1,6 @@
 {
-    "VoilaConfiguration": {
+    "Voila": {
         "template": "test_template",
         "enable_nbextensions": true
-    },
-    "MappingKernelManager": {
-        "cull_interval": 10
-    },
-    "LargeFileManager": {
-        "use_atomic_writing": false
     }
 }
diff --git a/voila/app.py b/voila/app.py
index 5968d35e3..8dd21c9a9 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -241,6 +241,9 @@ def _default_root_dir(self):
 
     default_url = Unicode("/voila", config=True)
 
+    def initialize_settings(self):
+        self.settings.update({ 'notebook_path': self.notebook_path })
+
     def initialize_templates(self):
         # common configuration options between the server extension and the application
         collect_template_paths(
diff --git a/voila/handler.py b/voila/handler.py
index e18c03b43..14fd5e8f2 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -31,6 +31,10 @@ def filter_empty_code_cells(cell, exporter):
 
 class VoilaHandler(ExtensionHandler):
 
+    @property
+    def notebook_path(self):
+        return self.settings['notebook_path']
+
     @tornado.web.authenticated
     @tornado.gen.coroutine
     def get(self, path=None):

From 1b18899ca8e2a1b240086fecdfbdcaa653534468 Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Tue, 10 Sep 2019 11:56:15 -0700
Subject: [PATCH 04/22] add tests back in one at a time

---
 tests/app/config_paths_test.py                |  2 +-
 tests/app/conftest.py                         | 48 +++++++++-----
 tests/app/cwd_subdir_test.py                  | 19 ------
 tests/app/cwd_test.py                         | 16 -----
 tests/app/execute_test.py                     | 66 -------------------
 tests/app/image_inlining_test.py              | 26 --------
 tests/app/nbextensions_test.py                | 31 ---------
 tests/app/no_kernelspec_test.py               | 18 -----
 tests/app/no_strip_sources_test.py            | 20 ------
 tests/app/non_existing_kernel_test.py         | 18 -----
 tests/app/notebooks_test.py                   | 14 ----
 tests/app/template_arg_test.py                | 15 -----
 tests/app/template_cli_test.py                | 20 ------
 tests/app/template_custom_test.py             | 31 ---------
 .../general/{voila.json => voila_config.json} |  0
 tests/server/__init__.py                      |  0
 tests/server/conftest.py                      | 46 -------------
 tests/server/cwd_subdir_test.py               | 20 ------
 tests/server/execute_test.py                  | 12 ----
 tests/server/nbextensions_test.py             | 25 -------
 tests/server/no_strip_sources_test.py         | 20 ------
 voila/app.py                                  |  6 +-
 voila/static_file_handler.py                  |  2 +-
 23 files changed, 37 insertions(+), 438 deletions(-)
 delete mode 100644 tests/app/cwd_subdir_test.py
 delete mode 100644 tests/app/cwd_test.py
 delete mode 100644 tests/app/execute_test.py
 delete mode 100644 tests/app/image_inlining_test.py
 delete mode 100644 tests/app/nbextensions_test.py
 delete mode 100644 tests/app/no_kernelspec_test.py
 delete mode 100644 tests/app/no_strip_sources_test.py
 delete mode 100644 tests/app/non_existing_kernel_test.py
 delete mode 100644 tests/app/notebooks_test.py
 delete mode 100644 tests/app/template_arg_test.py
 delete mode 100644 tests/app/template_cli_test.py
 delete mode 100644 tests/app/template_custom_test.py
 rename tests/configs/general/{voila.json => voila_config.json} (100%)
 delete mode 100644 tests/server/__init__.py
 delete mode 100644 tests/server/conftest.py
 delete mode 100644 tests/server/cwd_subdir_test.py
 delete mode 100644 tests/server/execute_test.py
 delete mode 100644 tests/server/nbextensions_test.py
 delete mode 100644 tests/server/no_strip_sources_test.py

diff --git a/tests/app/config_paths_test.py b/tests/app/config_paths_test.py
index 945831843..82bab2e12 100644
--- a/tests/app/config_paths_test.py
+++ b/tests/app/config_paths_test.py
@@ -10,7 +10,7 @@
 @pytest.fixture
 def voila_config_file_paths_arg():
     config_path = os.path.join(BASE_DIR, '..', 'configs', 'general')
-    return '--VoilaTest.config_file_paths=[%r]' % config_path
+    return '--Voila.config_file_paths=[%r]' % config_path
 
 def test_config_app(voila_app):
     assert voila_app.template == 'test_template'
diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 276f957c7..0f2aeeb68 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -2,19 +2,36 @@
 
 import pytest
 
-import voila.app
+from traitlets.config import Config
+from voila.app import Voila
+from jupyter_server.serverapp import ServerApp
 
 BASE_DIR = os.path.dirname(__file__)
 
 
-class VoilaTest(voila.app.Voila):
-    def listen(self):
-        pass  # the ioloop is taken care of by the pytest-tornado framework
+class ServerAppForTesting(ServerApp):
+    # pytest-tornado handles ioloop.
+    default_url = 'voila'
+
+    def start(self):
+        pass
+
+
+@pytest.fixture
+def server_args():
+    return []
+
+
+@pytest.fixture
+def serverapp(server_args):
+    serverapp = ServerAppForTesting()
+    serverapp.initialize(argv=server_args, load_extensions=False)
+    return serverapp
 
 
 @pytest.fixture
 def voila_config():
-    return lambda app: None
+    return {}
 
 
 @pytest.fixture
@@ -25,22 +42,21 @@ def voila_args_extra():
 @pytest.fixture
 def voila_config_file_paths_arg():
     # we don't want the tests to use any configuration on the system
-    return '--VoilaTest.config_file_paths=[]'
+    return '--Voila.config_file_paths=[]'
 
 
 @pytest.fixture
 def voila_args(voila_notebook, voila_args_extra, voila_config_file_paths_arg):
-    debug_args = ['--VoilaTest.log_level=DEBUG'] if os.environ.get('VOILA_TEST_DEBUG', False) else []
+    debug_args = ['--Voila.log_level=DEBUG'] if os.environ.get('VOILA_TEST_DEBUG', False) else []
     return [voila_notebook, voila_config_file_paths_arg] + voila_args_extra + debug_args
 
-
 @pytest.fixture
-def voila_app(voila_args, voila_config):
-    server_app = VoilaTest.initialize_server(argv=['--ServerApp.open_browser=False'])
-    voila_app = VoilaTest._prepare_launch(server_app, argv=voila_args)
-    voila_config(voila_app)
-    voila_app.start_server()
+def voila_app(serverapp, voila_args, voila_config):
+    config = Config(voila_config)
+    voila_app = Voila(config=config)
+    voila_app.initialize(serverapp, argv=voila_args)
     yield voila_app
-    server_app.stop()
-    server_app.clear_instance()
-    voila_app.clear_instance()
+
+@pytest.fixture
+def app(voila_app):
+    return voila_app.serverapp.web_app
\ No newline at end of file
diff --git a/tests/app/cwd_subdir_test.py b/tests/app/cwd_subdir_test.py
deleted file mode 100644
index ab8834aad..000000000
--- a/tests/app/cwd_subdir_test.py
+++ /dev/null
@@ -1,19 +0,0 @@
-# test serving a notebook
-import pytest
-
-
-@pytest.fixture
-def cwd_subdir_notebook_url(base_url):
-    return base_url + "/voila/render/subdir/cwd_subdir.ipynb"
-
-
-@pytest.fixture
-def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory, '--VoilaTest.log_level=DEBUG'] + voila_args_extra
-
-
-@pytest.mark.gen_test
-def test_hello_world(http_client, cwd_subdir_notebook_url):
-    response = yield http_client.fetch(cwd_subdir_notebook_url)
-    html_text = response.body.decode('utf-8')
-    assert 'check for the cwd' in html_text
diff --git a/tests/app/cwd_test.py b/tests/app/cwd_test.py
deleted file mode 100644
index 7bf1152f5..000000000
--- a/tests/app/cwd_test.py
+++ /dev/null
@@ -1,16 +0,0 @@
-# tests the --template argument of voila
-import pytest
-
-import os
-
-
-@pytest.fixture
-def voila_notebook(notebook_directory):
-    return os.path.join(notebook_directory, 'cwd.ipynb')
-
-
-@pytest.mark.gen_test
-def test_template_cwd(http_client, base_url, notebook_directory):
-    response = yield http_client.fetch(base_url)
-    html_text = response.body.decode('utf-8')
-    assert 'check for the cwd' in html_text
diff --git a/tests/app/execute_test.py b/tests/app/execute_test.py
deleted file mode 100644
index bf34b0234..000000000
--- a/tests/app/execute_test.py
+++ /dev/null
@@ -1,66 +0,0 @@
-# test basics of voila running a notebook
-import pytest
-
-import tornado.web
-import tornado.gen
-
-import re
-import json
-
-try:
-    from unittest import mock
-except ImportError:
-    import mock
-
-
-@pytest.mark.gen_test
-def test_hello_world(http_client, base_url):
-    response = yield http_client.fetch(base_url)
-    assert response.code == 200
-    html_text = response.body.decode('utf-8')
-    assert 'Hi Voila' in html_text
-    assert 'print' not in html_text, 'by default the source code should be stripped'
-    assert 'test_template.css' not in html_text, "test_template should not be the default"
-
-
-@pytest.mark.gen_test
-def test_no_execute_allowed(voila_app, app, http_client, base_url):
-    assert voila_app.app is app
-    response = (yield http_client.fetch(base_url)).body.decode('utf-8')
-    pattern = r"""kernelId": ["']([0-9a-zA-Z-]+)["']"""
-    groups = re.findall(pattern, response)
-    kernel_id = groups[0]
-    print(kernel_id, base_url)
-    session_id = '445edd75-c6f5-45d2-8b58-5fe8f84a7123'
-    url = '{base_url}/api/kernels/{kernel_id}/channels?session_id={session_id}'.format(
-        kernel_id=kernel_id, base_url=base_url, session_id=session_id
-    ).replace('http://', 'ws://')
-    conn = yield tornado.websocket.websocket_connect(url)
-
-    msg = {
-        "header": {
-            "msg_id": "8573fb401ac848aab63c3bf0081e9b65",
-            "username": "username",
-            "session": "7a7d94334ea745f888d9c479fa738d63",
-            "msg_type": "execute_request",
-            "version": "5.2",
-        },
-        "metadata": {},
-        "content": {
-            "code": "print('la')",
-            "silent": False,
-            "store_history": False,
-            "user_expressions": {},
-            "allow_stdin": False,
-            "stop_on_error": False,
-        },
-        "buffers": [],
-        "parent_header": {},
-        "channel": "shell",
-    }
-    with mock.patch.object(voila_app.log, 'warning') as mock_warning:
-        yield conn.write_message(json.dumps(msg))
-        # make sure the warning method is called
-        while not mock_warning.called:
-            yield tornado.gen.sleep(0.1)
-    mock_warning.assert_called_with('Received message of type "execute_request", which is not allowed. Ignoring.')
diff --git a/tests/app/image_inlining_test.py b/tests/app/image_inlining_test.py
deleted file mode 100644
index 70647ded2..000000000
--- a/tests/app/image_inlining_test.py
+++ /dev/null
@@ -1,26 +0,0 @@
-# tests the --template argument of voila
-import pytest
-
-import base64
-
-import os
-
-
-@pytest.fixture
-def voila_notebook(notebook_directory):
-    return os.path.join(notebook_directory, 'images.ipynb')
-
-
-@pytest.mark.gen_test
-def test_image_inlining(http_client, base_url, notebook_directory):
-    response = yield http_client.fetch(base_url)
-    html_text = response.body.decode('utf-8')
-
-    assert 'data:image/svg+xml;base64,' in html_text
-    assert 'data:image/png;base64,' in html_text
-
-    # check if the external file is inline
-    with open(os.path.join(notebook_directory, notebook_directory, 'quantstack.svg'), 'rb') as f:
-        svg_data = f.read()
-    svg_data_base64 = base64.b64encode(svg_data).decode('ascii')
-    assert svg_data_base64 in html_text
diff --git a/tests/app/nbextensions_test.py b/tests/app/nbextensions_test.py
deleted file mode 100644
index 1ec72010d..000000000
--- a/tests/app/nbextensions_test.py
+++ /dev/null
@@ -1,31 +0,0 @@
-# tests programmatic config of template sytem
-import pytest
-
-import os
-
-BASE_DIR = os.path.dirname(__file__)
-
-
-@pytest.fixture
-def voila_config():
-    def config(app):
-        pass
-    os.environ['JUPYTER_CONFIG_DIR'] = os.path.join(BASE_DIR, '../configs/general')
-    yield config
-    del os.environ['JUPYTER_CONFIG_DIR']
-
-
-@pytest.fixture
-def voila_config_file_paths_arg():
-    # we don't want the tests to use any configuration on the system
-    path = os.path.abspath(os.path.join(BASE_DIR, '../configs/general'))
-    return '--VoilaTest.config_file_paths=[%r]' % path
-
-
-@pytest.mark.gen_test
-def test_lists_extension(http_client, base_url):
-    response = yield http_client.fetch(base_url)
-    assert response.code == 200
-    html_text = response.body.decode('utf-8')
-    assert 'Hi Voila' in html_text
-    assert 'ipytest/extension.js' in html_text
diff --git a/tests/app/no_kernelspec_test.py b/tests/app/no_kernelspec_test.py
deleted file mode 100644
index 451dfde85..000000000
--- a/tests/app/no_kernelspec_test.py
+++ /dev/null
@@ -1,18 +0,0 @@
-import pytest
-
-
-@pytest.fixture
-def non_existing_kernel_notebook(base_url):
-    return base_url + "/voila/render/no_kernelspec.ipynb"
-
-
-@pytest.fixture
-def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory] + voila_args_extra
-
-
-@pytest.mark.gen_test
-def test_non_existing_kernel(http_client, non_existing_kernel_notebook):
-    response = yield http_client.fetch(non_existing_kernel_notebook)
-    assert response.code == 200
-    assert 'Executing without a kernelspec' in response.body.decode('utf-8')
diff --git a/tests/app/no_strip_sources_test.py b/tests/app/no_strip_sources_test.py
deleted file mode 100644
index f54cf8718..000000000
--- a/tests/app/no_strip_sources_test.py
+++ /dev/null
@@ -1,20 +0,0 @@
-import pytest
-
-import os
-
-
-BASE_DIR = os.path.dirname(__file__)
-
-
-@pytest.fixture
-def voila_args_extra():
-    return ['--VoilaConfiguration.strip_sources=False']
-
-
-@pytest.mark.gen_test
-def test_no_strip_sources(http_client, base_url):
-    response = yield http_client.fetch(base_url)
-    assert response.code == 200
-    html_text = response.body.decode('utf-8')
-    assert 'Hi Voila' in html_text
-    assert 'print' in html_text, 'the source code should *NOT* be stripped'
diff --git a/tests/app/non_existing_kernel_test.py b/tests/app/non_existing_kernel_test.py
deleted file mode 100644
index e588f8752..000000000
--- a/tests/app/non_existing_kernel_test.py
+++ /dev/null
@@ -1,18 +0,0 @@
-import pytest
-
-
-@pytest.fixture
-def non_existing_kernel_notebook(base_url):
-    return base_url + "/voila/render/non_existing_kernel.ipynb"
-
-
-@pytest.fixture
-def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory] + voila_args_extra
-
-
-@pytest.mark.gen_test
-def test_non_existing_kernel(http_client, non_existing_kernel_notebook):
-    response = yield http_client.fetch(non_existing_kernel_notebook)
-    assert response.code == 200
-    assert 'non-existing kernel' in response.body.decode('utf-8')
diff --git a/tests/app/notebooks_test.py b/tests/app/notebooks_test.py
deleted file mode 100644
index c3b9c0b34..000000000
--- a/tests/app/notebooks_test.py
+++ /dev/null
@@ -1,14 +0,0 @@
-# simply tests if some notebooks execute
-import pytest
-
-
-@pytest.fixture
-def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory, '--VoilaTest.log_level=DEBUG'] + voila_args_extra
-
-
-@pytest.mark.gen_test
-def test_other_comms(http_client, base_url):
-    response = yield http_client.fetch(base_url + '/voila/render/other_comms.ipynb')
-    html_text = response.body.decode('utf-8')
-    assert 'This notebook executed' in html_text
diff --git a/tests/app/template_arg_test.py b/tests/app/template_arg_test.py
deleted file mode 100644
index 4c4066c29..000000000
--- a/tests/app/template_arg_test.py
+++ /dev/null
@@ -1,15 +0,0 @@
-# tests the --template argument of voila
-import pytest
-
-
-@pytest.fixture
-def voila_args_extra():
-    return ['--template=test_template']
-
-
-@pytest.mark.gen_test
-def test_template(http_client, base_url):
-    response = yield http_client.fetch(base_url)
-    assert response.code == 200
-    assert 'test_template.css' in response.body.decode('utf-8')
-    assert 'Hi Voila' in response.body.decode('utf-8')
diff --git a/tests/app/template_cli_test.py b/tests/app/template_cli_test.py
deleted file mode 100644
index 2bfbcd8fc..000000000
--- a/tests/app/template_cli_test.py
+++ /dev/null
@@ -1,20 +0,0 @@
-# tests programmatic config of template sytem
-import pytest
-
-import os
-
-BASE_DIR = os.path.dirname(__file__)
-
-
-@pytest.fixture
-def voila_args_extra():
-    path_test_template = os.path.abspath(os.path.join(BASE_DIR, '../test_template/share/jupyter/voila/templates/test_template/nbconvert_templates'))
-    path_default = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default/nbconvert_templates'))
-    return ['--template=None', '--Voila.nbconvert_template_paths=[%r, %r]' % (path_test_template, path_default)]
-
-
-@pytest.mark.gen_test
-def test_template_test(http_client, base_url):
-    response = yield http_client.fetch(base_url)
-    assert response.code == 200
-    assert 'test_template.css' in response.body.decode('utf-8')
diff --git a/tests/app/template_custom_test.py b/tests/app/template_custom_test.py
deleted file mode 100644
index 08dab9c88..000000000
--- a/tests/app/template_custom_test.py
+++ /dev/null
@@ -1,31 +0,0 @@
-# tests programmatic config of template sytem
-import pytest
-
-import os
-
-BASE_DIR = os.path.dirname(__file__)
-
-
-@pytest.fixture
-def voila_args_extra():
-    return ['--template=None']
-
-
-@pytest.fixture
-def voila_config():
-    def config(app):
-        path_test_template = os.path.abspath(os.path.join(BASE_DIR, '../test_template/share/jupyter/voila/templates/test_template/nbconvert_templates'))
-        path_default = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default/nbconvert_templates'))
-        app.nbconvert_template_paths = [path_test_template, path_default]
-        path = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default/templates'))
-        app.template_paths = [path]
-
-    return config
-
-
-@pytest.mark.gen_test
-def test_template(http_client, base_url):
-    response = yield http_client.fetch(base_url)
-    assert response.code == 200
-    assert 'test_template.css' in response.body.decode('utf-8')
-    assert 'Hi Voila' in response.body.decode('utf-8')
diff --git a/tests/configs/general/voila.json b/tests/configs/general/voila_config.json
similarity index 100%
rename from tests/configs/general/voila.json
rename to tests/configs/general/voila_config.json
diff --git a/tests/server/__init__.py b/tests/server/__init__.py
deleted file mode 100644
index e69de29bb..000000000
diff --git a/tests/server/conftest.py b/tests/server/conftest.py
deleted file mode 100644
index e37b7e2e6..000000000
--- a/tests/server/conftest.py
+++ /dev/null
@@ -1,46 +0,0 @@
-import os
-
-import pytest
-
-from jupyter_server.serverapp import ServerApp
-
-from tornado import httpserver
-
-
-BASE_DIR = os.path.dirname(__file__)
-
-
-@pytest.fixture
-def jupyter_server_config():
-    return lambda app: None
-
-
-@pytest.fixture
-def jupyter_server_args_extra():
-    return []
-
-
-@pytest.fixture
-def jupyter_server_args(notebook_directory, jupyter_server_args_extra):
-    debug_args = ['--ServerApp.log_level=DEBUG'] if os.environ.get('VOILA_TEST_DEBUG', False) else []
-    default_args = ['--ServerApp.token=""']
-    return [notebook_directory] + jupyter_server_args_extra + debug_args + default_args
-
-
-@pytest.fixture
-def jupyter_server_app(jupyter_server_args, jupyter_server_config):
-    jupyter_server_app = ServerApp.instance()
-    # we monkey patch
-    old_listen = httpserver.HTTPServer.listen
-    httpserver.HTTPServer.listen = lambda *x, **y: None
-    # NOTE: in voila's conftest.py we call config after initialize
-    jupyter_server_config(jupyter_server_app)
-    jupyter_server_app.initialize(jupyter_server_args)
-    yield jupyter_server_app
-    httpserver.HTTPServer.listen = old_listen
-    ServerApp.clear_instance()
-
-
-@pytest.fixture
-def app(jupyter_server_app):
-    return jupyter_server_app.web_app
diff --git a/tests/server/cwd_subdir_test.py b/tests/server/cwd_subdir_test.py
deleted file mode 100644
index 6bdad3d13..000000000
--- a/tests/server/cwd_subdir_test.py
+++ /dev/null
@@ -1,20 +0,0 @@
-# NOTE: this is a duplicate of ../app/cwd_subdir_test.py
-# we might want to find a better pattern of executing test for the app and extension
-import pytest
-
-
-@pytest.fixture
-def cwd_subdir_notebook_url(base_url):
-    return base_url + "/voila/render/subdir/cwd_subdir.ipynb"
-
-
-@pytest.fixture
-def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory, '--VoilaTest.log_level=DEBUG'] + voila_args_extra
-
-
-@pytest.mark.gen_test
-def test_hello_world(http_client, cwd_subdir_notebook_url):
-    response = yield http_client.fetch(cwd_subdir_notebook_url)
-    html_text = response.body.decode('utf-8')
-    assert 'check for the cwd' in html_text
diff --git a/tests/server/execute_test.py b/tests/server/execute_test.py
deleted file mode 100644
index 801c35e6c..000000000
--- a/tests/server/execute_test.py
+++ /dev/null
@@ -1,12 +0,0 @@
-# test basics of voila running a notebook
-import pytest
-
-
-@pytest.mark.gen_test
-def test_hello_world(http_client, print_notebook_url):
-    response = yield http_client.fetch(print_notebook_url)
-    assert response.code == 200
-    html_text = response.body.decode('utf-8')
-    assert 'Hi Voila' in html_text
-    assert 'print' not in html_text, 'by default the source code should be stripped'
-    assert 'test_template.css' not in html_text, "test_template should not be the default"
diff --git a/tests/server/nbextensions_test.py b/tests/server/nbextensions_test.py
deleted file mode 100644
index 66a057652..000000000
--- a/tests/server/nbextensions_test.py
+++ /dev/null
@@ -1,25 +0,0 @@
-# tests programmatic config of template sytem
-import pytest
-
-import os
-
-BASE_DIR = os.path.dirname(__file__)
-
-
-@pytest.fixture
-def jupyter_server_config():
-    def config(app):
-        pass
-    os.environ['JUPYTER_CONFIG_DIR'] = os.path.join(BASE_DIR, '..', 'configs', 'general')
-    yield config
-    del os.environ['JUPYTER_CONFIG_DIR']
-
-
-@pytest.mark.xfail(reason='needs to be fixed')
-@pytest.mark.gen_test
-def test_lists_extension(http_client, print_notebook_url):
-    response = yield http_client.fetch(print_notebook_url)
-    assert response.code == 200
-    html_text = response.body.decode('utf-8')
-    assert 'Hi Voila' in html_text
-    assert 'ipytest/extension.js' in html_text
diff --git a/tests/server/no_strip_sources_test.py b/tests/server/no_strip_sources_test.py
deleted file mode 100644
index 47cd20976..000000000
--- a/tests/server/no_strip_sources_test.py
+++ /dev/null
@@ -1,20 +0,0 @@
-import pytest
-
-import os
-
-
-BASE_DIR = os.path.dirname(__file__)
-
-
-@pytest.fixture
-def jupyter_server_args_extra():
-    return ['--VoilaConfiguration.strip_sources=False']
-
-
-@pytest.mark.gen_test
-def test_hello_world(http_client, print_notebook_url):
-    response = yield http_client.fetch(print_notebook_url)
-    assert response.code == 200
-    html_text = response.body.decode('utf-8')
-    assert 'Hi Voila' in html_text
-    assert 'print' in html_text, 'the source code should *NOT* be stripped'
diff --git a/voila/app.py b/voila/app.py
index 8dd21c9a9..8da53935d 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -69,8 +69,8 @@ class Voila(ExtensionApp):
     name = 'voila'
     version = __version__
     examples = 'jupyter voila example.ipynb'
-    extension_name = 'voila'
-
+    load_other_extensions = False
+    
     flags = {
         'debug': ({'Voila': {'log_level': logging.DEBUG}}, _("Set the log level to logging.DEBUG")),
         'no-browser': ({'Voila': {'open_browser': False}}, _('Don\'t open the notebook in a browser after startup.')),
@@ -134,7 +134,7 @@ class Voila(ExtensionApp):
         help="""
         extra resources used by templates;
         example use with --template=reveal
-        --VoilaConfiguration.resources="{'reveal': {'transition': 'fade', 'scroll': True}}"
+        --Volia.resources="{'reveal': {'transition': 'fade', 'scroll': True}}"
         """
     ).tag(config=True)
     theme = Unicode('light').tag(config=True)
diff --git a/voila/static_file_handler.py b/voila/static_file_handler.py
index fe0293942..b8e1e63ab 100644
--- a/voila/static_file_handler.py
+++ b/voila/static_file_handler.py
@@ -33,7 +33,7 @@ def initialize(self, paths, default_filename=None):
     def get_absolute_path(self, root, path):
         # find the first absolute path that exists
         self.root = self.roots[0]
-        for root in self.roots:git 
+        for root in self.roots: 
             abspath = os.path.abspath(os.path.join(root, path))
             if os.path.exists(abspath):
                 self.root = root  # make sure all the other methods in the base class know how to find the file

From 2835e6c4108ac43768c82ba2fba9ddc2c33373c3 Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Tue, 10 Sep 2019 20:40:38 -0700
Subject: [PATCH 05/22] update various tests with auth token

---
 tests/app/config_paths_test.py        |  7 ++++---
 tests/app/conftest.py                 | 20 +++++++++++++-----
 tests/app/cwd_subdir_test.py          | 19 ++++++++++++++++++
 tests/app/cwd_test.py                 | 15 ++++++++++++++
 tests/app/image_inlining_test.py      | 24 ++++++++++++++++++++++
 tests/app/no_strip_sources_test.py    | 20 ++++++++++++++++++
 tests/app/non_existing_kernel_test.py | 18 +++++++++++++++++
 tests/app/notebooks_test.py           | 15 ++++++++++++++
 tests/app/serve_directory_test.py     |  4 ++--
 tests/app/template_arg_test.py        | 15 ++++++++++++++
 voila/app.py                          | 29 ++++++++++++++++++++-------
 voila/handler.py                      |  9 +++++++--
 12 files changed, 176 insertions(+), 19 deletions(-)
 create mode 100644 tests/app/cwd_subdir_test.py
 create mode 100644 tests/app/cwd_test.py
 create mode 100644 tests/app/image_inlining_test.py
 create mode 100644 tests/app/no_strip_sources_test.py
 create mode 100644 tests/app/non_existing_kernel_test.py
 create mode 100644 tests/app/notebooks_test.py
 create mode 100644 tests/app/template_arg_test.py

diff --git a/tests/app/config_paths_test.py b/tests/app/config_paths_test.py
index 82bab2e12..5057813fd 100644
--- a/tests/app/config_paths_test.py
+++ b/tests/app/config_paths_test.py
@@ -1,6 +1,5 @@
 # test all objects that should be configurable
 import pytest
-
 import os
 
 
@@ -12,13 +11,15 @@ def voila_config_file_paths_arg():
     config_path = os.path.join(BASE_DIR, '..', 'configs', 'general')
     return '--Voila.config_file_paths=[%r]' % config_path
 
+
 def test_config_app(voila_app):
     assert voila_app.template == 'test_template'
     assert voila_app.enable_nbextensions is True
 
+
 @pytest.mark.gen_test
-def test_template(http_client, base_url):
-    response = yield http_client.fetch(base_url)
+def test_template(http_client, default_url):
+    response = yield http_client.fetch(default_url)
     assert response.code == 200
     assert 'test_template.css' in response.body.decode('utf-8')
     assert 'Hi Voila' in response.body.decode('utf-8')
diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 0f2aeeb68..7b903d43f 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -23,11 +23,10 @@ def server_args():
 
 
 @pytest.fixture
-def serverapp(server_args):
-    serverapp = ServerAppForTesting()
+def serverapp(notebook_directory, server_args):
+    serverapp = ServerAppForTesting(root_dir=notebook_directory)
     serverapp.initialize(argv=server_args, load_extensions=False)
-    return serverapp
-
+    yield serverapp
 
 @pytest.fixture
 def voila_config():
@@ -59,4 +58,15 @@ def voila_app(serverapp, voila_args, voila_config):
 
 @pytest.fixture
 def app(voila_app):
-    return voila_app.serverapp.web_app
\ No newline at end of file
+    return voila_app.serverapp.web_app
+
+@pytest.fixture
+def add_token(serverapp):
+    '''Add a token to any url.'''
+    def add_token_to_url(url):
+        return url + '?token={}'.format(serverapp.token)
+    return add_token_to_url
+
+@pytest.fixture
+def default_url(base_url, add_token):
+    return add_token(base_url)
\ No newline at end of file
diff --git a/tests/app/cwd_subdir_test.py b/tests/app/cwd_subdir_test.py
new file mode 100644
index 000000000..b79bdf080
--- /dev/null
+++ b/tests/app/cwd_subdir_test.py
@@ -0,0 +1,19 @@
+# test serving a notebook
+import pytest
+
+@pytest.fixture
+def cwd_subdir_notebook_url(base_url):
+    return base_url + "/voila/render/subdir/cwd_subdir.ipynb"
+
+
+@pytest.fixture
+def voila_args(notebook_directory, voila_args_extra):
+    return ['--Voila.root_dir=%r' % notebook_directory, '--Voila.log_level=DEBUG'] + voila_args_extra
+
+
+@pytest.mark.gen_test
+def test_hello_world(http_client, add_token, cwd_subdir_notebook_url):
+    url = add_token(cwd_subdir_notebook_url)
+    response = yield http_client.fetch(url)
+    html_text = response.body.decode('utf-8')
+    assert 'check for the cwd' in html_text
diff --git a/tests/app/cwd_test.py b/tests/app/cwd_test.py
new file mode 100644
index 000000000..f98759f5f
--- /dev/null
+++ b/tests/app/cwd_test.py
@@ -0,0 +1,15 @@
+# tests the --template argument of voila
+import pytest
+import os
+
+
+@pytest.fixture
+def voila_notebook(notebook_directory):
+    return os.path.join(notebook_directory, 'cwd.ipynb')
+
+
+@pytest.mark.gen_test
+def test_template_cwd(http_client, default_url):
+    response = yield http_client.fetch(default_url)
+    html_text = response.body.decode('utf-8')
+    assert 'check for the cwd' in html_text
diff --git a/tests/app/image_inlining_test.py b/tests/app/image_inlining_test.py
new file mode 100644
index 000000000..7896c802b
--- /dev/null
+++ b/tests/app/image_inlining_test.py
@@ -0,0 +1,24 @@
+# tests the --template argument of voila
+import pytest
+import base64
+import os
+
+
+@pytest.fixture
+def voila_notebook(notebook_directory):
+    return os.path.join(notebook_directory, 'images.ipynb')
+
+
+@pytest.mark.gen_test
+def test_image_inlining(http_client, default_url, notebook_directory):
+    response = yield http_client.fetch(default_url)
+    html_text = response.body.decode('utf-8')
+
+    assert 'data:image/svg+xml;base64,' in html_text
+    assert 'data:image/png;base64,' in html_text
+
+    # check if the external file is inline
+    with open(os.path.join(notebook_directory, notebook_directory, 'quantstack.svg'), 'rb') as f:
+        svg_data = f.read()
+    svg_data_base64 = base64.b64encode(svg_data).decode('ascii')
+    assert svg_data_base64 in html_text
diff --git a/tests/app/no_strip_sources_test.py b/tests/app/no_strip_sources_test.py
new file mode 100644
index 000000000..a7760a2a6
--- /dev/null
+++ b/tests/app/no_strip_sources_test.py
@@ -0,0 +1,20 @@
+import pytest
+
+import os
+
+
+BASE_DIR = os.path.dirname(__file__)
+
+
+@pytest.fixture
+def voila_args_extra():
+    return ['--Voila.strip_sources=False']
+
+
+@pytest.mark.gen_test
+def test_no_strip_sources(http_client, default_url):
+    response = yield http_client.fetch(default_url)
+    assert response.code == 200
+    html_text = response.body.decode('utf-8')
+    assert 'Hi Voila' in html_text
+    assert 'print' in html_text, 'the source code should *NOT* be stripped'
diff --git a/tests/app/non_existing_kernel_test.py b/tests/app/non_existing_kernel_test.py
new file mode 100644
index 000000000..4d7d5242d
--- /dev/null
+++ b/tests/app/non_existing_kernel_test.py
@@ -0,0 +1,18 @@
+import pytest
+
+
+@pytest.fixture
+def non_existing_kernel_notebook(base_url):
+    return base_url + "/voila/render/non_existing_kernel.ipynb"
+
+
+@pytest.fixture
+def voila_args(notebook_directory, voila_args_extra):
+    return ['--Voila.root_dir=%r' % notebook_directory] + voila_args_extra
+
+
+@pytest.mark.gen_test
+def test_non_existing_kernel(http_client, add_token, non_existing_kernel_notebook):
+    response = yield http_client.fetch(add_token(non_existing_kernel_notebook))
+    assert response.code == 200
+    assert 'non-existing kernel' in response.body.decode('utf-8')
diff --git a/tests/app/notebooks_test.py b/tests/app/notebooks_test.py
new file mode 100644
index 000000000..e43cc2c09
--- /dev/null
+++ b/tests/app/notebooks_test.py
@@ -0,0 +1,15 @@
+# simply tests if some notebooks execute
+import pytest
+
+
+@pytest.fixture
+def voila_args(notebook_directory, voila_args_extra):
+    return ['--Voila.root_dir=%r' % notebook_directory, '--Voila.log_level=DEBUG'] + voila_args_extra
+
+
+@pytest.mark.gen_test
+def test_other_comms(http_client, add_token, base_url):
+    url = add_token(base_url + '/voila/render/other_comms.ipynb')
+    response = yield http_client.fetch(url)
+    html_text = response.body.decode('utf-8')
+    assert 'This notebook executed' in html_text
diff --git a/tests/app/serve_directory_test.py b/tests/app/serve_directory_test.py
index 6f5ba4c30..bf88d1431 100644
--- a/tests/app/serve_directory_test.py
+++ b/tests/app/serve_directory_test.py
@@ -7,7 +7,7 @@
 
 @pytest.fixture
 def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory, '--VoilaTest.log_level=DEBUG'] + voila_args_extra
+    return ['--Voila.root_dir=%r' % notebook_directory] + voila_args_extra
 
 
 @pytest.mark.gen_test
@@ -20,7 +20,7 @@ def test_print(http_client, print_notebook_url):
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--VoilaConfiguration.extension_language_mapping={".py": "python"}']
+    return ['--Voila.extension_language_mapping={".py": "python"}']
 
 
 @pytest.mark.gen_test
diff --git a/tests/app/template_arg_test.py b/tests/app/template_arg_test.py
new file mode 100644
index 000000000..5d424a874
--- /dev/null
+++ b/tests/app/template_arg_test.py
@@ -0,0 +1,15 @@
+# tests the --template argument of voila
+import pytest
+
+
+@pytest.fixture
+def voila_args_extra():
+    return ['--template=test_template']
+
+
+@pytest.mark.gen_test
+def test_template(http_client, default_url):
+    response = yield http_client.fetch(default_url)
+    assert response.code == 200
+    assert 'test_template.css' in response.body.decode('utf-8')
+    assert 'Hi Voila' in response.body.decode('utf-8')
diff --git a/voila/app.py b/voila/app.py
index 8da53935d..d6a00f47a 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -238,10 +238,22 @@ def _default_root_dir(self):
         else:
             return getcwd()
 
-
     default_url = Unicode("/voila", config=True)
+    
+    def parse_command_line(self, argv=None):
+        super(Voila, self).parse_command_line(argv)
+        # Catch first argument as notebook path.
+        if self.extra_args:
+            notebook_path = self.extra_args[0]
+            f = os.path.abspath(notebook_path)
+            self.argv.remove(notebook_path)
+            if not os.path.exists(f):
+                self.log.critical(_("No such file or directory: %s"), f)
+                self.exit(1)
+            self.notebook_path = notebook_path
 
     def initialize_settings(self):
+        self.serverapp.root_dir = self.root_dir
         self.settings.update({ 'notebook_path': self.notebook_path })
 
     def initialize_templates(self):
@@ -262,11 +274,14 @@ def initialize_templates(self):
         self.settings.update(**template_settings)
 
     def initialize_handlers(self):
-        handlers = [
-            ('/voila/render' + path_regex, VoilaHandler),
-            ('/voila', VoilaTreeHandler),
-            ('/voila/tree' + path_regex, VoilaTreeHandler),
-        ]
-        self.handlers.extend(handlers)
+        if self.notebook_path:
+            self.handlers.append(('/voila', VoilaHandler))
+        else:
+            handlers = [
+                ('/voila/render' + path_regex, VoilaHandler),
+                ('/voila', VoilaTreeHandler),
+                ('/voila/tree' + path_regex, VoilaTreeHandler),
+            ]
+            self.handlers.extend(handlers)
 
 main = Voila.launch_instance
diff --git a/voila/handler.py b/voila/handler.py
index 14fd5e8f2..cded8738c 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -11,6 +11,7 @@
 
 import tornado.web
 
+from jupyter_server.utils import url_path_join
 from jupyter_server.extension.handler import ExtensionHandler
 from jupyter_server.config_manager import recursive_update
 from nbconvert.preprocessors import ClearOutputPreprocessor
@@ -33,7 +34,11 @@ class VoilaHandler(ExtensionHandler):
 
     @property
     def notebook_path(self):
-        return self.settings['notebook_path']
+        path = self.settings.get('notebook_path', None)
+        # Get relative path to notebook.
+        if path is not None:
+            path = os.path.relpath(path, self.config['root_dir'])
+        return path
 
     @tornado.web.authenticated
     @tornado.gen.coroutine
@@ -41,7 +46,7 @@ def get(self, path=None):
         # if the handler got a notebook_path argument, always serve that
         notebook_path = self.notebook_path or path
         if self.notebook_path and path:  # when we are in single notebook mode but have a path
-            self.redirect_to_file(path)
+            self.redirect_to_fiççle(path)
             return
 
         if self.config.enable_nbextensions:

From 32f87e757195689642f9b4c2892fa86dc399d97a Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Wed, 11 Sep 2019 17:37:31 -0700
Subject: [PATCH 06/22] add 4 more tests back in

---
 tests/app/conftest.py             | 13 +++++-
 tests/app/no_kernelspec_test.py   | 18 ++++++++
 tests/app/template_cli_test.py    | 20 +++++++++
 tests/app/template_custom_test.py | 31 +++++++++++++
 voila/app.py                      | 72 ++++++++++++++++++++++++++++---
 voila/handler.py                  |  1 +
 6 files changed, 146 insertions(+), 9 deletions(-)
 create mode 100644 tests/app/no_kernelspec_test.py
 create mode 100644 tests/app/template_cli_test.py
 create mode 100644 tests/app/template_custom_test.py

diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 7b903d43f..856881737 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -1,5 +1,5 @@
 import os
-
+import urllib
 import pytest
 
 from traitlets.config import Config
@@ -64,7 +64,16 @@ def app(voila_app):
 def add_token(serverapp):
     '''Add a token to any url.'''
     def add_token_to_url(url):
-        return url + '?token={}'.format(serverapp.token)
+        parts = list(urllib.parse.urlparse(url))
+        if parts[4] == '':
+            query = 'token={}'.format(serverapp.token)
+        else:
+            query = '{q}&token={token}'.format(
+                q=parts[4], 
+                token=serverapp.token)
+        parts[4] = query
+        new_url = urllib.parse.urlunparse(parts)
+        return new_url
     return add_token_to_url
 
 @pytest.fixture
diff --git a/tests/app/no_kernelspec_test.py b/tests/app/no_kernelspec_test.py
new file mode 100644
index 000000000..b23f7e70f
--- /dev/null
+++ b/tests/app/no_kernelspec_test.py
@@ -0,0 +1,18 @@
+import pytest
+
+
+@pytest.fixture
+def non_existing_kernel_notebook(base_url):
+    return base_url + "/voila/render/no_kernelspec.ipynb"
+
+
+@pytest.fixture
+def voila_args(notebook_directory, voila_args_extra):
+    return ['--Voila.root_dir=%r' % notebook_directory] + voila_args_extra
+
+
+@pytest.mark.gen_test
+def test_non_existing_kernel(http_client, add_token, non_existing_kernel_notebook):
+    response = yield http_client.fetch(add_token(non_existing_kernel_notebook))
+    assert response.code == 200
+    assert 'Executing without a kernelspec' in response.body.decode('utf-8')
diff --git a/tests/app/template_cli_test.py b/tests/app/template_cli_test.py
new file mode 100644
index 000000000..28a6c8326
--- /dev/null
+++ b/tests/app/template_cli_test.py
@@ -0,0 +1,20 @@
+# tests programmatic config of template sytem
+import pytest
+
+import os
+
+BASE_DIR = os.path.dirname(__file__)
+
+
+@pytest.fixture
+def voila_args_extra():
+    path_test_template = os.path.abspath(os.path.join(BASE_DIR, '../test_template/share/jupyter/voila/templates/test_template/nbconvert_templates'))
+    path_default = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default/nbconvert_templates'))
+    return ['--template=None', '--Voila.nbconvert_template_paths=[%r, %r]' % (path_test_template, path_default)]
+
+
+@pytest.mark.gen_test
+def test_template_test(http_client, default_url):
+    response = yield http_client.fetch(default_url)
+    assert response.code == 200
+    assert 'test_template.css' in response.body.decode('utf-8')
diff --git a/tests/app/template_custom_test.py b/tests/app/template_custom_test.py
new file mode 100644
index 000000000..1fa0af767
--- /dev/null
+++ b/tests/app/template_custom_test.py
@@ -0,0 +1,31 @@
+# tests programmatic config of template sytem
+import pytest
+
+import os
+
+BASE_DIR = os.path.dirname(__file__)
+
+
+@pytest.fixture
+def voila_args_extra():
+    return ['--template=None']
+
+
+@pytest.fixture
+def voila_config():
+    path_test_template = os.path.abspath(os.path.join(BASE_DIR, '../test_template/share/jupyter/voila/templates/test_template/nbconvert_templates'))
+    path_default = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default/nbconvert_templates'))
+    path = os.path.abspath(os.path.join(BASE_DIR, '../../share/jupyter/voila/templates/default/templates'))
+    config = dict(
+        nbconvert_template_paths=[path_test_template, path_default],
+        template_paths=[path]
+    )
+    return config
+
+
+@pytest.mark.gen_test
+def test_template(http_client, default_url):
+    response = yield http_client.fetch(default_url)
+    assert response.code == 200
+    assert 'test_template.css' in response.body.decode('utf-8')
+    assert 'Hi Voila' in response.body.decode('utf-8')
diff --git a/voila/app.py b/voila/app.py
index d6a00f47a..1a6c161f9 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -52,6 +52,7 @@
 from .paths import ROOT, STATIC_ROOT, collect_template_paths
 from .handler import VoilaHandler
 from .treehandler import VoilaTreeHandler
+from .static_file_handler import WhiteListFileHandler
 from ._version import __version__
 from .execute import VoilaExecutePreprocessor
 from .exporter import VoilaExporter
@@ -129,6 +130,30 @@ class Voila(ExtensionApp):
             'template name to be used by voila.'
         )
     )
+
+    file_whitelist = List(
+        Unicode(),
+        [r'.*\.(png|jpg|gif|svg)'],
+        help=r"""
+        List of regular expressions for controlling which static files are served.
+        All files that are served should at least match 1 whitelist rule, and no blacklist rule
+        Example: --VoilaConfiguration.file_whitelist="['.*\.(png|jpg|gif|svg)', 'public.*']"
+        """,
+    ).tag(config=True)
+
+    file_blacklist = List(
+        Unicode(),
+        [r'.*\.(ipynb|py)'],
+        help=r"""
+        List of regular expressions for controlling which static files are forbidden to be served.
+        All files that are served should at least match 1 whitelist rule, and no blacklist rule
+        Example:
+        --VoilaConfiguration.file_whitelist="['.*']" # all files
+        --VoilaConfiguration.file_blacklist="['private.*', '.*\.(ipynb)']" # except files in the private dir and notebook files
+        """
+    ).tag(config=True)
+
+
     resources = Dict(
         allow_none=True,
         help="""
@@ -137,6 +162,7 @@ class Voila(ExtensionApp):
         --Volia.resources="{'reveal': {'transition': 'fade', 'scroll': True}}"
         """
     ).tag(config=True)
+
     theme = Unicode('light').tag(config=True)
     strip_sources = Bool(True, help='Strip sources from rendered html').tag(config=True)
     enable_nbextensions = Bool(False, config=True, help=('Set to True for Voila to load notebook extensions'))
@@ -257,13 +283,20 @@ def initialize_settings(self):
         self.settings.update({ 'notebook_path': self.notebook_path })
 
     def initialize_templates(self):
-        # common configuration options between the server extension and the application
-        collect_template_paths(
-            self.nbconvert_template_paths,
-            self.static_paths,
-            self.template_paths,
-            self.template
-        )
+        if self.template:
+            # common configuration options between the server extension and the application
+            collect_template_paths(
+                self.nbconvert_template_paths,
+                self.static_paths,
+                self.template_paths,
+                self.template
+            )
+
+        self.serverapp.log.debug('using template: %s', self.template)
+        self.serverapp.log.debug('nbconvert template paths:\n\t%s', '\n\t'.join(self.nbconvert_template_paths))
+        self.serverapp.log.debug('template paths:\n\t%s', '\n\t'.join(self.template_paths))
+        self.serverapp.log.debug('static paths:\n\t%s', '\n\t'.join(self.static_paths))
+
         jenv_opt = {"autoescape": True}
         env = jinja2.Environment(loader=jinja2.FileSystemLoader(self.template_paths), extensions=['jinja2.ext.i18n'], **jenv_opt)
 
@@ -274,6 +307,31 @@ def initialize_templates(self):
         self.settings.update(**template_settings)
 
     def initialize_handlers(self):
+        # Serving notebook extensions
+        if self.enable_nbextensions:
+            self.handlers.append(
+                (
+                    '/voila/nbextensions/(.*)', 
+                    FileFindHandler,
+                    {
+                        'path': self.nbextensions_path,
+                        'no_cache_paths': ['/']
+                    }
+                )
+            )
+
+        self.handlers.append(
+            (
+                '/voila/files/(.*)', 
+                WhiteListFileHandler,
+                {
+                    'whitelist': self.file_whitelist,
+                    'blacklist': self.file_blacklist,
+                    'path': self.root_dir,
+                }
+            )
+        )
+        
         if self.notebook_path:
             self.handlers.append(('/voila', VoilaHandler))
         else:
diff --git a/voila/handler.py b/voila/handler.py
index cded8738c..bbd34033d 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -11,6 +11,7 @@
 
 import tornado.web
 
+import nbformat
 from jupyter_server.utils import url_path_join
 from jupyter_server.extension.handler import ExtensionHandler
 from jupyter_server.config_manager import recursive_update

From df8c6bf1c66e6beda76de957eac607a0b3022d89 Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Thu, 12 Sep 2019 11:17:21 -0700
Subject: [PATCH 07/22] nbextensions_test passing

---
 tests/app/nbextensions_test.py                | 28 +++++++++++++++++++
 .../notebook.d/ipytest.json                   |  0
 2 files changed, 28 insertions(+)
 create mode 100644 tests/app/nbextensions_test.py
 rename tests/configs/general/{nbconfig => serverconfig}/notebook.d/ipytest.json (100%)

diff --git a/tests/app/nbextensions_test.py b/tests/app/nbextensions_test.py
new file mode 100644
index 000000000..05dd3e606
--- /dev/null
+++ b/tests/app/nbextensions_test.py
@@ -0,0 +1,28 @@
+# tests programmatic config of template sytem
+import pytest
+import os
+
+BASE_DIR = os.path.dirname(__file__)
+
+
+@pytest.fixture
+def voila_config():
+    os.environ['JUPYTER_CONFIG_DIR'] = os.path.join(BASE_DIR, '../configs/general')
+    yield {}
+    del os.environ['JUPYTER_CONFIG_DIR']
+
+
+@pytest.fixture
+def voila_config_file_paths_arg():
+    # we don't want the tests to use any configuration on the system
+    path = os.path.abspath(os.path.join(BASE_DIR, '../configs/general'))
+    return '--Voila.config_file_paths=[%r]' % path
+
+
+@pytest.mark.gen_test
+def test_lists_extension(http_client, default_url):
+    response = yield http_client.fetch(default_url)
+    assert response.code == 200
+    html_text = response.body.decode('utf-8')
+    assert 'Hi Voila' in html_text
+    assert 'ipytest/extension.js' in html_text
diff --git a/tests/configs/general/nbconfig/notebook.d/ipytest.json b/tests/configs/general/serverconfig/notebook.d/ipytest.json
similarity index 100%
rename from tests/configs/general/nbconfig/notebook.d/ipytest.json
rename to tests/configs/general/serverconfig/notebook.d/ipytest.json

From 4399ed9105bff91a3a86bbdb6eb485344ac56529 Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Thu, 12 Sep 2019 11:44:48 -0700
Subject: [PATCH 08/22] modify serverapp configmanager to capture nbconfig

---
 .../notebook.d/ipytest.json                   |  0
 voila/app.py                                  | 22 ++++++++++++++++++-
 voila/handler.py                              |  2 +-
 3 files changed, 22 insertions(+), 2 deletions(-)
 rename tests/configs/general/{serverconfig => nbconfig}/notebook.d/ipytest.json (100%)

diff --git a/tests/configs/general/serverconfig/notebook.d/ipytest.json b/tests/configs/general/nbconfig/notebook.d/ipytest.json
similarity index 100%
rename from tests/configs/general/serverconfig/notebook.d/ipytest.json
rename to tests/configs/general/nbconfig/notebook.d/ipytest.json
diff --git a/voila/app.py b/voila/app.py
index 1a6c161f9..2e16e6f33 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -67,6 +67,7 @@ def _(x):
 
 
 class Voila(ExtensionApp):
+
     name = 'voila'
     version = __version__
     examples = 'jupyter voila example.ipynb'
@@ -99,7 +100,9 @@ class Voila(ExtensionApp):
             'Will autoreload to server and the page when a template, js file or Python code changes'
         )
     )
+
     root_dir = Unicode(config=True, help=_('The directory to use for notebooks.'))
+    
     static_root = Unicode(
         STATIC_ROOT,
         config=True,
@@ -107,6 +110,7 @@ class Voila(ExtensionApp):
             'Directory holding static assets (HTML, JS and CSS files).'
         )
     )
+    
     aliases = {
         'port': 'ServerApp.port',
         'static': 'Voila.static_root',
@@ -116,6 +120,7 @@ class Voila(ExtensionApp):
         'theme': 'Voila.theme',
         'enable_nbextensions': 'Voila.enable_nbextensions',
     }
+    
     classes = [
         VoilaExecutePreprocessor,
         VoilaExporter,
@@ -153,7 +158,6 @@ class Voila(ExtensionApp):
         """
     ).tag(config=True)
 
-
     resources = Dict(
         allow_none=True,
         help="""
@@ -164,7 +168,9 @@ class Voila(ExtensionApp):
     ).tag(config=True)
 
     theme = Unicode('light').tag(config=True)
+    
     strip_sources = Bool(True, help='Strip sources from rendered html').tag(config=True)
+    
     enable_nbextensions = Bool(False, config=True, help=('Set to True for Voila to load notebook extensions'))
 
     connection_dir_root = Unicode(
@@ -279,7 +285,21 @@ def parse_command_line(self, argv=None):
             self.notebook_path = notebook_path
 
     def initialize_settings(self):
+        # Ensure the server finds both serverconfig and nbconfig.
+        paths = self.serverapp.config_manager.read_config_path
+        for p in jupyter_config_path():
+            paths.extend([
+                os.path.join(p, 'serverconfig'),
+                os.path.join(p, 'nbconfig')
+            ])
+        # Keep unique paths.
+        paths = list(set(paths))
+        self.serverapp.config_manager.read_config_path = paths
+
+        # Set the serverapp root_dir to be the same as voila.
         self.serverapp.root_dir = self.root_dir
+
+        # Pass notebook path to settings.
         self.settings.update({ 'notebook_path': self.notebook_path })
 
     def initialize_templates(self):
diff --git a/voila/handler.py b/voila/handler.py
index bbd34033d..fe1d3f9bf 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -47,7 +47,7 @@ def get(self, path=None):
         # if the handler got a notebook_path argument, always serve that
         notebook_path = self.notebook_path or path
         if self.notebook_path and path:  # when we are in single notebook mode but have a path
-            self.redirect_to_fiççle(path)
+            self.redirect_to_file(path)
             return
 
         if self.config.enable_nbextensions:

From baf1ab6d8f2e807eb5cf810d5aac856287b20432 Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Thu, 12 Sep 2019 15:04:22 -0700
Subject: [PATCH 09/22] added last test

---
 tests/app/conftest.py     | 51 +++++++++++++----------------
 tests/app/execute_test.py | 67 +++++++++++++++++++++++++++++++++++++++
 voila/app.py              | 46 +++++++++++++++++++++++++--
 3 files changed, 132 insertions(+), 32 deletions(-)
 create mode 100644 tests/app/execute_test.py

diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 856881737..94364d6b2 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -2,36 +2,25 @@
 import urllib
 import pytest
 
-from traitlets.config import Config
 from voila.app import Voila
 from jupyter_server.serverapp import ServerApp
 
 BASE_DIR = os.path.dirname(__file__)
 
 
-class ServerAppForTesting(ServerApp):
-    # pytest-tornado handles ioloop.
-    default_url = 'voila'
-
-    def start(self):
-        pass
-
-
-@pytest.fixture
-def server_args():
-    return []
-
-
 @pytest.fixture
-def serverapp(notebook_directory, server_args):
-    serverapp = ServerAppForTesting(root_dir=notebook_directory)
-    serverapp.initialize(argv=server_args, load_extensions=False)
-    yield serverapp
+def voila_config(notebook_directory):
+    return dict(
+        root_dir=notebook_directory,
+    )
 
 @pytest.fixture
-def voila_config():
-    return {}
-
+def server_config(notebook_directory):
+    return dict(
+        root_dir=notebook_directory,
+        default_url='voila',
+        log_level='DEBUG'
+    )
 
 @pytest.fixture
 def voila_args_extra():
@@ -46,13 +35,17 @@ def voila_config_file_paths_arg():
 
 @pytest.fixture
 def voila_args(voila_notebook, voila_args_extra, voila_config_file_paths_arg):
-    debug_args = ['--Voila.log_level=DEBUG'] if os.environ.get('VOILA_TEST_DEBUG', False) else []
-    return [voila_notebook, voila_config_file_paths_arg] + voila_args_extra + debug_args
+    return [voila_notebook, voila_config_file_paths_arg] + voila_args_extra
 
 @pytest.fixture
-def voila_app(serverapp, voila_args, voila_config):
-    config = Config(voila_config)
-    voila_app = Voila(config=config)
+def voila_app(server_config, voila_args, voila_config):
+    # Get an instance of Voila
+    voila_app = Voila(**voila_config)
+    # Get an instance of the underlying server. This is
+    # configured automatically when launched by command line.
+    serverapp = voila_app.initialize_server(**server_config)
+    # silence the start method for pytests.
+    serverapp.start = lambda self: None
     voila_app.initialize(serverapp, argv=voila_args)
     yield voila_app
 
@@ -61,16 +54,16 @@ def app(voila_app):
     return voila_app.serverapp.web_app
 
 @pytest.fixture
-def add_token(serverapp):
+def add_token(voila_app):
     '''Add a token to any url.'''
     def add_token_to_url(url):
         parts = list(urllib.parse.urlparse(url))
         if parts[4] == '':
-            query = 'token={}'.format(serverapp.token)
+            query = 'token={}'.format(voila_app.serverapp.token)
         else:
             query = '{q}&token={token}'.format(
                 q=parts[4], 
-                token=serverapp.token)
+                token=voila_app.serverapp.token)
         parts[4] = query
         new_url = urllib.parse.urlunparse(parts)
         return new_url
diff --git a/tests/app/execute_test.py b/tests/app/execute_test.py
new file mode 100644
index 000000000..0dc38589f
--- /dev/null
+++ b/tests/app/execute_test.py
@@ -0,0 +1,67 @@
+# test basics of voila running a notebook
+import pytest
+
+import tornado.web
+import tornado.gen
+
+import re
+import json
+
+try:
+    from unittest import mock
+except ImportError:
+    import mock
+
+
+# @pytest.mark.gen_test
+# def test_hello_world(http_client, default_url):
+#     response = yield http_client.fetch(default_url)
+#     assert response.code == 200
+#     html_text = response.body.decode('utf-8')
+#     assert 'Hi Voila' in html_text
+#     assert 'print' not in html_text, 'by default the source code should be stripped'
+#     assert 'test_template.css' not in html_text, "test_template should not be the default"
+
+
+@pytest.mark.gen_test
+def test_no_execute_allowed(voila_app, app, http_client, add_token, base_url):
+    url_to_request = add_token(base_url)
+    response = (yield http_client.fetch(url_to_request)).body.decode('utf-8')
+    pattern = r"""kernelId": ["']([0-9a-zA-Z-]+)["']"""
+    groups = re.findall(pattern, response)
+    kernel_id = groups[0]
+    session_id = '445edd75-c6f5-45d2-8b58-5fe8f84a7123'
+    url = '{base_url}/api/kernels/{kernel_id}/channels?session_id={session_id}'.format(
+        kernel_id=kernel_id, base_url=base_url, session_id=session_id
+    ).replace('http://', 'ws://')
+    url = add_token(url)
+    conn = yield tornado.websocket.websocket_connect(url)
+    msg = {
+        "header": {
+            "msg_id": "8573fb401ac848aab63c3bf0081e9b65",
+            "username": "username",
+            "session": "7a7d94334ea745f888d9c479fa738d63",
+            "msg_type": "execute_request",
+            "version": "5.2",
+        },
+        "metadata": {},
+        "content": {
+            "code": "print('la')",
+            "silent": False,
+            "store_history": False,
+            "user_expressions": {},
+            "allow_stdin": False,
+            "stop_on_error": False,
+        },
+        "buffers": [],
+        "parent_header": {},
+        "channel": "shell",
+    }
+    obj = voila_app.serverapp
+    with mock.patch.object(obj.log, 'warning') as mock_warning:
+        yield conn.write_message(json.dumps(msg))
+        # make sure the warning method is called
+        while not mock_warning.called:
+            yield tornado.gen.sleep(0.1)
+
+    mock_warning.assert_called_with('Received message of type "execute_request", which is not allowed. Ignoring.')
diff --git a/voila/app.py b/voila/app.py
index 2e16e6f33..2288673ed 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -34,9 +34,11 @@
 import tornado.ioloop
 import tornado.web
 
+from traitlets.config import Config
 from traitlets.config.application import Application
 from traitlets import Unicode, Integer, Bool, Dict, List, default
 
+from jupyter_server.serverapp import ServerApp
 from jupyter_server.services.kernels.kernelmanager import MappingKernelManager
 from jupyter_server.services.kernels.handlers import KernelHandler, ZMQChannelsHandler
 from jupyter_server.services.contents.largefilemanager import LargeFileManager
@@ -74,7 +76,7 @@ class Voila(ExtensionApp):
     load_other_extensions = False
     
     flags = {
-        'debug': ({'Voila': {'log_level': logging.DEBUG}}, _("Set the log level to logging.DEBUG")),
+        'debug': ({'ServerApp': {'log_level': logging.DEBUG}}, _("Set the log level to logging.DEBUG")),
         'no-browser': ({'Voila': {'open_browser': False}}, _('Don\'t open the notebook in a browser after startup.')),
         'standalone': ({'ServerApp': {'standalone': True}}, _('Run the server without enabling extensions.'))
     }
@@ -158,6 +160,22 @@ class Voila(ExtensionApp):
         """
     ).tag(config=True)
 
+    language_kernel_mapping = Dict(
+        {},
+        help="""Mapping of language name to kernel name
+        Example mapping python to use xeus-python, and C++11 to use xeus-cling:
+        --VoilaConfiguration.extension_language_mapping='{"python": "xpython", "C++11": "xcpp11"}'
+        """,
+    ).tag(config=True)
+
+    extension_language_mapping = Dict(
+        {},
+        help='''Mapping of file extension to kernel language
+        Example mapping .py files to a python language kernel, and .cpp to a C++11 language kernel:
+        --VoilaConfiguration.extension_language_mapping='{".py": "python", ".cpp": "C++11"}'
+        ''',
+    ).tag(config=True)
+
     resources = Dict(
         allow_none=True,
         help="""
@@ -284,6 +302,28 @@ def parse_command_line(self, argv=None):
                 self.exit(1)
             self.notebook_path = notebook_path
 
+    @staticmethod
+    def initialize_server(argv=[], load_other_extensions=False, **kwargs):
+        """Get an instance of the Jupyter Server."""
+        config = {
+            'ServerApp': {
+                'MappingKernelManager': {
+                    'allowed_message_types': [
+                        'comm_msg',
+                        'comm_info_request',
+                        'kernel_info_request',
+                        'shutdown_request'
+                    ]
+                }
+            }
+        }
+        return ExtensionApp.initialize_server(
+            argv=argv, 
+            load_other_extensions=load_other_extensions,
+            config=Config(config),
+            **kwargs
+        )
+
     def initialize_settings(self):
         # Ensure the server finds both serverconfig and nbconfig.
         paths = self.serverapp.config_manager.read_config_path
@@ -296,8 +336,8 @@ def initialize_settings(self):
         paths = list(set(paths))
         self.serverapp.config_manager.read_config_path = paths
 
-        # Set the serverapp root_dir to be the same as voila.
-        self.serverapp.root_dir = self.root_dir
+        # # Set the serverapp root_dir to be the same as voila.
+        # self.serverapp.root_dir = self.root_dir
 
         # Pass notebook path to settings.
         self.settings.update({ 'notebook_path': self.notebook_path })

From 0e18ec10b55b6a9b98c35ad89f5d96022be5ebfb Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Thu, 12 Sep 2019 15:34:28 -0700
Subject: [PATCH 10/22] update tests from rebase with changes to voila

---
 tests/app/execute_cpp_test.py     |  8 ++++----
 tests/app/serve_directory_test.py |  3 +++
 tests/app/tree_test.py            |  8 ++++----
 tests/server/execute_cpp_test.py  | 27 ---------------------------
 tests/server/tree_test.py         | 22 ----------------------
 voila/handler.py                  | 20 ++++++++++++--------
 voila/treehandler.py              |  4 ++++
 7 files changed, 27 insertions(+), 65 deletions(-)
 delete mode 100644 tests/server/execute_cpp_test.py
 delete mode 100644 tests/server/tree_test.py

diff --git a/tests/app/execute_cpp_test.py b/tests/app/execute_cpp_test.py
index 5cbd5c5aa..a8a803590 100644
--- a/tests/app/execute_cpp_test.py
+++ b/tests/app/execute_cpp_test.py
@@ -5,18 +5,18 @@
 
 
 @pytest.fixture
-def cpp_file_url(base_url):
-    return base_url + "/voila/render/print.xcpp"
+def cpp_file_url(base_url, add_token):
+    return add_token(base_url + "/voila/render/print.xcpp")
 
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--VoilaConfiguration.extension_language_mapping={".xcpp": "C++11"}']
+    return ['--Voila.extension_language_mapping={".xcpp": "C++11"}']
 
 
 @pytest.fixture
 def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory] + voila_args_extra
+    return ['--Voila.root_dir=%r' % notebook_directory] + voila_args_extra
 
 
 @pytest.mark.skipif(not TEST_XEUS_CLING, reason='opt in to avoid having to install xeus-cling')
diff --git a/tests/app/serve_directory_test.py b/tests/app/serve_directory_test.py
index bf88d1431..73a9627bd 100644
--- a/tests/app/serve_directory_test.py
+++ b/tests/app/serve_directory_test.py
@@ -9,6 +9,9 @@
 def voila_args(notebook_directory, voila_args_extra):
     return ['--Voila.root_dir=%r' % notebook_directory] + voila_args_extra
 
+@pytest.fixture
+def print_notebook_url(add_token, print_notebook_url):
+    return add_token(print_notebook_url)
 
 @pytest.mark.gen_test
 def test_print(http_client, print_notebook_url):
diff --git a/tests/app/tree_test.py b/tests/app/tree_test.py
index be6fc64f7..335392cd7 100644
--- a/tests/app/tree_test.py
+++ b/tests/app/tree_test.py
@@ -4,17 +4,17 @@
 
 @pytest.fixture
 def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory, '--VoilaTest.log_level=DEBUG'] + voila_args_extra
+    return ['--Voila.root_dir=%r' % notebook_directory] + voila_args_extra
 
 
 @pytest.fixture
 def voila_args_extra():
-    return ['--VoilaConfiguration.extension_language_mapping={".xcpp": "C++11"}']
+    return ['--Voila.extension_language_mapping={".xcpp": "C++11"}']
 
 
 @pytest.mark.gen_test
-def test_tree(http_client, base_url):
-    response = yield http_client.fetch(base_url)
+def test_tree(http_client, default_url):
+    response = yield http_client.fetch(default_url)
     assert response.code == 200
     text = response.body.decode('utf-8')
     assert 'print.ipynb' in text, 'tree handler should render ipynb files'
diff --git a/tests/server/execute_cpp_test.py b/tests/server/execute_cpp_test.py
deleted file mode 100644
index 9684e7439..000000000
--- a/tests/server/execute_cpp_test.py
+++ /dev/null
@@ -1,27 +0,0 @@
-import os
-import pytest
-
-TEST_XEUS_CLING = os.environ.get('VOILA_TEST_XEUS_CLING', '') == '1'
-
-
-@pytest.fixture
-def cpp_file_url(base_url):
-    return base_url + "/voila/render/print.xcpp"
-
-
-@pytest.fixture
-def jupyter_server_args_extra():
-    return ['--VoilaConfiguration.extension_language_mapping={".xcpp": "C++11"}']
-
-
-@pytest.fixture
-def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory] + voila_args_extra
-
-
-@pytest.mark.skipif(not TEST_XEUS_CLING, reason='opt in to avoid having to install xeus-cling')
-@pytest.mark.gen_test
-def test_non_existing_kernel(http_client, cpp_file_url):
-    response = yield http_client.fetch(cpp_file_url)
-    assert response.code == 200
-    assert 'Hello voila, from c++' in response.body.decode('utf-8')
diff --git a/tests/server/tree_test.py b/tests/server/tree_test.py
deleted file mode 100644
index 3846abc70..000000000
--- a/tests/server/tree_test.py
+++ /dev/null
@@ -1,22 +0,0 @@
-# test tree rendering
-import pytest
-
-
-@pytest.fixture
-def voila_args(notebook_directory, voila_args_extra):
-    return ['--VoilaTest.root_dir=%r' % notebook_directory, '--VoilaTest.log_level=DEBUG'] + voila_args_extra
-
-
-@pytest.fixture
-def jupyter_server_args_extra():
-    return ['--VoilaConfiguration.extension_language_mapping={".xcpp": "C++11"}']
-
-
-@pytest.mark.gen_test
-def test_tree(http_client, base_url):
-    response = yield http_client.fetch(base_url+'/voila/tree')
-    assert response.code == 200
-    text = response.body.decode('utf-8')
-    assert 'print.ipynb' in text, 'tree handler should render ipynb files'
-    assert 'print.xcpp' in text, 'tree handler should render xcpp files (due to extension_language_mapping)'
-    assert 'print.py' not in text, 'tree handler should not render .py files (due to extension_language_mapping)'
diff --git a/voila/handler.py b/voila/handler.py
index fe1d3f9bf..121eec7a8 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -33,6 +33,10 @@ def filter_empty_code_cells(cell, exporter):
 
 class VoilaHandler(ExtensionHandler):
 
+    def initialize(self, **kwargs):
+        self.kernel_started = False
+        super(VoilaHandler, self).initialize(**kwargs)
+
     @property
     def notebook_path(self):
         path = self.settings.get('notebook_path', None)
@@ -70,9 +74,9 @@ def get(self, path=None):
         self.cwd = os.path.dirname(notebook_path)
 
         # Launch kernel and execute notebook
-        kernel_id = yield tornado.gen.maybe_future(self.kernel_manager.start_kernel(kernel_name=notebook.metadata.kernelspec.name, path=self.cwd))
+        kernel_id = yield tornado.gen.maybe_future(self.kernel_manager.start_kernel(kernel_name=self.notebook.metadata.kernelspec.name, path=self.cwd))
         km = self.kernel_manager.get_kernel(kernel_id)
-        result = executenb(notebook, km=km, cwd=self.cwd, config=self.server_config)
+        result = executenb(self.notebook, km=km, cwd=self.cwd, config=self.server_config)
 
         # render notebook to html
         resources = {
@@ -129,7 +133,7 @@ def _jinja_kernel_start(self):
 
     def _jinja_notebook_execute(self, nb, kernel_id):
         km = self.kernel_manager.get_kernel(kernel_id)
-        result = executenb(nb, km=km, cwd=self.cwd, config=self.traitlet_config)
+        result = executenb(nb, km=km, cwd=self.cwd, config=self.server_config)
         result.cells = list(filter(lambda cell: filter_empty_code_cells(cell, self.exporter), result.cells))
         # we modify the notebook in place, since the nb variable cannot be reassigned it seems in jinja2
         # e.g. if we do {% with nb = notebook_execute(nb, kernel_id) %}, the base template/blocks will not
@@ -141,7 +145,7 @@ def _jinja_cell_generator(self, nb, kernel_id):
         km = self.kernel_manager.get_kernel(kernel_id)
 
         nb, resources = ClearOutputPreprocessor().preprocess(nb, {'metadata': {'path': self.cwd}})
-        ep = VoilaExecutePreprocessor(config=self.traitlet_config)
+        ep = VoilaExecutePreprocessor(config=self.server_config)
 
         with ep.setup_preprocessor(nb, resources, km=km):
             for cell_idx, cell in enumerate(nb.cells):
@@ -159,8 +163,8 @@ def load_notebook(self, path):
             notebook = model['content']
             notebook = yield self.fix_notebook(notebook)
             raise tornado.gen.Return(notebook)  # TODO py2: replace by return
-        elif extension in self.voila_configuration.extension_language_mapping:
-            language = self.voila_configuration.extension_language_mapping[extension]
+        elif extension in self.config.extension_language_mapping:
+            language = self.config.extension_language_mapping[extension]
             notebook = yield self.create_notebook(model, language=language)
             raise tornado.gen.Return(notebook)  # TODO py2: replace by return
         else:
@@ -215,8 +219,8 @@ def find_kernel_name_for_language(self, kernel_language, kernel_specs=None):
 
         If multiple kernels matches are found, we try to return the same kernel name each time.
         """
-        if kernel_language in self.voila_configuration.language_kernel_mapping:
-            raise tornado.gen.Return(self.voila_configuration.language_kernel_mapping[kernel_language])  # TODO py2: replace by return
+        if kernel_language in self.config.language_kernel_mapping:
+            raise tornado.gen.Return(self.config.language_kernel_mapping[kernel_language])  # TODO py2: replace by return
         if kernel_specs is None:
             kernel_specs = yield tornado.gen.maybe_future(self.kernel_spec_manager.get_all_specs())
         matches = [
diff --git a/voila/treehandler.py b/voila/treehandler.py
index 1ee6ac59c..c556a57ce 100644
--- a/voila/treehandler.py
+++ b/voila/treehandler.py
@@ -18,6 +18,10 @@
 
 class VoilaTreeHandler(ExtensionHandler):
 
+    def initialize(self, **kwargs):
+        super(VoilaTreeHandler, self).initialize(**kwargs)
+        self.allowed_extensions = list(self.config.extension_language_mapping.keys()) + ['.ipynb']
+
     def get_template(self, name):
         """Return the jinja template object for a given name"""
         return self.settings['voila_jinja2_env'].get_template(name)

From d47ab694c2ef424cf28043aca601d522f592c21c Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Thu, 12 Sep 2019 15:39:35 -0700
Subject: [PATCH 11/22] uncomment test

---
 tests/app/execute_test.py | 16 ++++++++--------
 1 file changed, 8 insertions(+), 8 deletions(-)

diff --git a/tests/app/execute_test.py b/tests/app/execute_test.py
index 0dc38589f..7e94a710e 100644
--- a/tests/app/execute_test.py
+++ b/tests/app/execute_test.py
@@ -13,14 +13,14 @@
     import mock
 
 
-# @pytest.mark.gen_test
-# def test_hello_world(http_client, default_url):
-#     response = yield http_client.fetch(default_url)
-#     assert response.code == 200
-#     html_text = response.body.decode('utf-8')
-#     assert 'Hi Voila' in html_text
-#     assert 'print' not in html_text, 'by default the source code should be stripped'
-#     assert 'test_template.css' not in html_text, "test_template should not be the default"
+@pytest.mark.gen_test
+def test_hello_world(http_client, default_url):
+    response = yield http_client.fetch(default_url)
+    assert response.code == 200
+    html_text = response.body.decode('utf-8')
+    assert 'Hi Voila' in html_text
+    assert 'print' not in html_text, 'by default the source code should be stripped'
+    assert 'test_template.css' not in html_text, "test_template should not be the default"
 
 
 @pytest.mark.gen_test

From ad00928b7f0fd900fe1f878d4c395923247f614d Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Fri, 13 Sep 2019 10:33:14 -0700
Subject: [PATCH 12/22] pass flake8

---
 tests/app/conftest.py             |  36 +++--
 tests/app/cwd_subdir_test.py      |  10 +-
 tests/app/serve_directory_test.py |  22 ++-
 voila/__init__.py                 |   1 +
 voila/app.py                      | 258 +++++++++++++-----------------
 voila/handler.py                  | 147 +++++++++++------
 voila/static_file_handler.py      |   2 +-
 7 files changed, 252 insertions(+), 224 deletions(-)

diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 94364d6b2..482166b8b 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -3,24 +3,20 @@
 import pytest
 
 from voila.app import Voila
-from jupyter_server.serverapp import ServerApp
+
 
 BASE_DIR = os.path.dirname(__file__)
 
 
 @pytest.fixture
 def voila_config(notebook_directory):
-    return dict(
-        root_dir=notebook_directory,
-    )
+    return dict(root_dir=notebook_directory)
+
 
 @pytest.fixture
 def server_config(notebook_directory):
-    return dict(
-        root_dir=notebook_directory,
-        default_url='voila',
-        log_level='DEBUG'
-    )
+    return dict(root_dir=notebook_directory, default_url="voila", log_level="DEBUG")
+
 
 @pytest.fixture
 def voila_args_extra():
@@ -30,13 +26,14 @@ def voila_args_extra():
 @pytest.fixture
 def voila_config_file_paths_arg():
     # we don't want the tests to use any configuration on the system
-    return '--Voila.config_file_paths=[]'
+    return "--Voila.config_file_paths=[]"
 
 
 @pytest.fixture
 def voila_args(voila_notebook, voila_args_extra, voila_config_file_paths_arg):
     return [voila_notebook, voila_config_file_paths_arg] + voila_args_extra
 
+
 @pytest.fixture
 def voila_app(server_config, voila_args, voila_config):
     # Get an instance of Voila
@@ -49,26 +46,31 @@ def voila_app(server_config, voila_args, voila_config):
     voila_app.initialize(serverapp, argv=voila_args)
     yield voila_app
 
+
 @pytest.fixture
 def app(voila_app):
     return voila_app.serverapp.web_app
 
+
 @pytest.fixture
 def add_token(voila_app):
-    '''Add a token to any url.'''
+    """Add a token to any url."""
+
     def add_token_to_url(url):
         parts = list(urllib.parse.urlparse(url))
-        if parts[4] == '':
-            query = 'token={}'.format(voila_app.serverapp.token)
+        if parts[4] == "":
+            query = "token={}".format(voila_app.serverapp.token)
         else:
-            query = '{q}&token={token}'.format(
-                q=parts[4], 
-                token=voila_app.serverapp.token)
+            query = "{q}&token={token}".format(
+                q=parts[4], token=voila_app.serverapp.token
+            )
         parts[4] = query
         new_url = urllib.parse.urlunparse(parts)
         return new_url
+
     return add_token_to_url
 
+
 @pytest.fixture
 def default_url(base_url, add_token):
-    return add_token(base_url)
\ No newline at end of file
+    return add_token(base_url)
diff --git a/tests/app/cwd_subdir_test.py b/tests/app/cwd_subdir_test.py
index b79bdf080..881790c2c 100644
--- a/tests/app/cwd_subdir_test.py
+++ b/tests/app/cwd_subdir_test.py
@@ -1,6 +1,7 @@
 # test serving a notebook
 import pytest
 
+
 @pytest.fixture
 def cwd_subdir_notebook_url(base_url):
     return base_url + "/voila/render/subdir/cwd_subdir.ipynb"
@@ -8,12 +9,15 @@ def cwd_subdir_notebook_url(base_url):
 
 @pytest.fixture
 def voila_args(notebook_directory, voila_args_extra):
-    return ['--Voila.root_dir=%r' % notebook_directory, '--Voila.log_level=DEBUG'] + voila_args_extra
+    return [
+        "--Voila.root_dir=%r" % notebook_directory,
+        "--Voila.log_level=DEBUG",
+    ] + voila_args_extra
 
 
 @pytest.mark.gen_test
 def test_hello_world(http_client, add_token, cwd_subdir_notebook_url):
     url = add_token(cwd_subdir_notebook_url)
     response = yield http_client.fetch(url)
-    html_text = response.body.decode('utf-8')
-    assert 'check for the cwd' in html_text
+    html_text = response.body.decode("utf-8")
+    assert "check for the cwd" in html_text
diff --git a/tests/app/serve_directory_test.py b/tests/app/serve_directory_test.py
index 73a9627bd..6ad341a09 100644
--- a/tests/app/serve_directory_test.py
+++ b/tests/app/serve_directory_test.py
@@ -2,23 +2,25 @@
 import os
 import pytest
 
-TEST_XEUS_CLING = os.environ.get('VOILA_TEST_XEUS_CLING', '') == '1'
+TEST_XEUS_CLING = os.environ.get("VOILA_TEST_XEUS_CLING", "") == "1"
 
 
 @pytest.fixture
 def voila_args(notebook_directory, voila_args_extra):
-    return ['--Voila.root_dir=%r' % notebook_directory] + voila_args_extra
+    return ["--Voila.root_dir=%r" % notebook_directory] + voila_args_extra
+
 
 @pytest.fixture
 def print_notebook_url(add_token, print_notebook_url):
     return add_token(print_notebook_url)
 
+
 @pytest.mark.gen_test
 def test_print(http_client, print_notebook_url):
     print(print_notebook_url)
     response = yield http_client.fetch(print_notebook_url)
     assert response.code == 200
-    assert 'Hi Voila' in response.body.decode('utf-8')
+    assert "Hi Voila" in response.body.decode("utf-8")
 
 
 @pytest.fixture
@@ -29,15 +31,19 @@ def voila_args_extra():
 @pytest.mark.gen_test
 def test_print_py(http_client, print_notebook_url):
     print(print_notebook_url)
-    response = yield http_client.fetch(print_notebook_url.replace('ipynb', 'py'))
+    response = yield http_client.fetch(print_notebook_url.replace("ipynb", "py"))
     assert response.code == 200
-    assert 'Hi Voila' in response.body.decode('utf-8')
+    assert "Hi Voila" in response.body.decode("utf-8")
 
 
-@pytest.mark.skipif(not TEST_XEUS_CLING, reason='opt in to avoid having to install xeus-cling')
+@pytest.mark.skipif(
+    not TEST_XEUS_CLING, reason="opt in to avoid having to install xeus-cling"
+)
 @pytest.mark.gen_test
 def test_print_julia_notebook(http_client, print_notebook_url):
     print(print_notebook_url)
-    response = yield http_client.fetch(print_notebook_url.replace('.ipynb', '_cpp.ipynb'))
+    response = yield http_client.fetch(
+        print_notebook_url.replace(".ipynb", "_cpp.ipynb")
+    )
     assert response.code == 200
-    assert 'Hi Voila, from c++' in response.body.decode('utf-8')
+    assert "Hi Voila, from c++" in response.body.decode("utf-8")
diff --git a/voila/__init__.py b/voila/__init__.py
index c9897f132..155066df6 100644
--- a/voila/__init__.py
+++ b/voila/__init__.py
@@ -12,6 +12,7 @@
 
 load_jupyter_server_extension = Voila.load_jupyter_server_extension
 
+
 def _jupyter_nbextension_paths():
     return [dict(
         section="notebook",
diff --git a/voila/app.py b/voila/app.py
index 2288673ed..546797cf8 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -10,41 +10,15 @@
 from zmq.eventloop import ioloop
 
 import gettext
-import io
 import logging
-import threading
-import tempfile
 import os
-import shutil
-import signal
-import socket
-import webbrowser
-import errno
-import random
-
-try:
-    from urllib.parse import urljoin
-    from urllib.request import pathname2url
-except ImportError:
-    from urllib import pathname2url
-    from urlparse import urljoin
 
 import jinja2
 
-import tornado.ioloop
-import tornado.web
-
 from traitlets.config import Config
-from traitlets.config.application import Application
 from traitlets import Unicode, Integer, Bool, Dict, List, default
 
-from jupyter_server.serverapp import ServerApp
-from jupyter_server.services.kernels.kernelmanager import MappingKernelManager
-from jupyter_server.services.kernels.handlers import KernelHandler, ZMQChannelsHandler
-from jupyter_server.services.contents.largefilemanager import LargeFileManager
 from jupyter_server.base.handlers import path_regex
-from jupyter_server.utils import url_path_join
-from jupyter_server.services.config import ConfigManager
 from jupyter_server.base.handlers import FileFindHandler
 from jupyter_server.extension.application import ExtensionApp
 from jupyter_core.paths import jupyter_config_path, jupyter_path
@@ -70,15 +44,24 @@ def _(x):
 
 class Voila(ExtensionApp):
 
-    name = 'voila'
+    name = "voila"
     version = __version__
-    examples = 'jupyter voila example.ipynb'
+    examples = "jupyter voila example.ipynb"
     load_other_extensions = False
-    
+
     flags = {
-        'debug': ({'ServerApp': {'log_level': logging.DEBUG}}, _("Set the log level to logging.DEBUG")),
-        'no-browser': ({'Voila': {'open_browser': False}}, _('Don\'t open the notebook in a browser after startup.')),
-        'standalone': ({'ServerApp': {'standalone': True}}, _('Run the server without enabling extensions.'))
+        "debug": (
+            {"ServerApp": {"log_level": logging.DEBUG}},
+            _("Set the log level to logging.DEBUG"),
+        ),
+        "no-browser": (
+            {"Voila": {"open_browser": False}},
+            _("Don't open the notebook in a browser after startup."),
+        ),
+        "standalone": (
+            {"ServerApp": {"standalone": True}},
+            _("Run the server without enabling extensions."),
+        ),
     }
 
     description = Unicode(
@@ -99,48 +82,40 @@ class Voila(ExtensionApp):
         False,
         config=True,
         help=_(
-            'Will autoreload to server and the page when a template, js file or Python code changes'
-        )
+            "Will autoreload to server and the page when a template, js file or Python code changes"
+        ),
     )
 
-    root_dir = Unicode(config=True, help=_('The directory to use for notebooks.'))
-    
+    root_dir = Unicode(config=True, help=_("The directory to use for notebooks."))
+
     static_root = Unicode(
         STATIC_ROOT,
         config=True,
-        help=_(
-            'Directory holding static assets (HTML, JS and CSS files).'
-        )
+        help=_("Directory holding static assets (HTML, JS and CSS files)."),
     )
-    
+
     aliases = {
-        'port': 'ServerApp.port',
-        'static': 'Voila.static_root',
-        'strip_sources': 'Voila.strip_sources',
-        'autoreload': 'Voila.autoreload',
-        'template': 'Voila.template',
-        'theme': 'Voila.theme',
-        'enable_nbextensions': 'Voila.enable_nbextensions',
+        "port": "ServerApp.port",
+        "static": "Voila.static_root",
+        "strip_sources": "Voila.strip_sources",
+        "autoreload": "Voila.autoreload",
+        "template": "Voila.template",
+        "theme": "Voila.theme",
+        "enable_nbextensions": "Voila.enable_nbextensions",
     }
-    
-    classes = [
-        VoilaExecutePreprocessor,
-        VoilaExporter,
-        VoilaCSSPreprocessor
-    ]
+
+    classes = [VoilaExecutePreprocessor, VoilaExporter, VoilaCSSPreprocessor]
 
     template = Unicode(
-        'default',
+        "default",
         config=True,
         allow_none=True,
-        help=(
-            'template name to be used by voila.'
-        )
+        help=("template name to be used by voila."),
     )
 
     file_whitelist = List(
         Unicode(),
-        [r'.*\.(png|jpg|gif|svg)'],
+        [r".*\.(png|jpg|gif|svg)"],
         help=r"""
         List of regular expressions for controlling which static files are served.
         All files that are served should at least match 1 whitelist rule, and no blacklist rule
@@ -150,14 +125,14 @@ class Voila(ExtensionApp):
 
     file_blacklist = List(
         Unicode(),
-        [r'.*\.(ipynb|py)'],
+        [r".*\.(ipynb|py)"],
         help=r"""
         List of regular expressions for controlling which static files are forbidden to be served.
         All files that are served should at least match 1 whitelist rule, and no blacklist rule
         Example:
         --VoilaConfiguration.file_whitelist="['.*']" # all files
         --VoilaConfiguration.file_blacklist="['private.*', '.*\.(ipynb)']" # except files in the private dir and notebook files
-        """
+        """,
     ).tag(config=True)
 
     language_kernel_mapping = Dict(
@@ -170,10 +145,10 @@ class Voila(ExtensionApp):
 
     extension_language_mapping = Dict(
         {},
-        help='''Mapping of file extension to kernel language
+        help="""Mapping of file extension to kernel language
         Example mapping .py files to a python language kernel, and .cpp to a C++11 language kernel:
         --VoilaConfiguration.extension_language_mapping='{".py": "python", ".cpp": "C++11"}'
-        ''',
+        """,
     ).tag(config=True)
 
     resources = Dict(
@@ -182,21 +157,23 @@ class Voila(ExtensionApp):
         extra resources used by templates;
         example use with --template=reveal
         --Volia.resources="{'reveal': {'transition': 'fade', 'scroll': True}}"
-        """
+        """,
     ).tag(config=True)
 
-    theme = Unicode('light').tag(config=True)
-    
-    strip_sources = Bool(True, help='Strip sources from rendered html').tag(config=True)
-    
-    enable_nbextensions = Bool(False, config=True, help=('Set to True for Voila to load notebook extensions'))
+    theme = Unicode("light").tag(config=True)
+
+    strip_sources = Bool(True, help="Strip sources from rendered html").tag(config=True)
+
+    enable_nbextensions = Bool(
+        False, config=True, help=("Set to True for Voila to load notebook extensions")
+    )
 
     connection_dir_root = Unicode(
         config=True,
         help=_(
-            'Location of temporry connection files. Defaults '
-            'to system `tempfile.gettempdir()` value.'
-        )
+            "Location of temporry connection files. Defaults "
+            "to system `tempfile.gettempdir()` value."
+        ),
     )
     connection_dir = Unicode()
 
@@ -204,38 +181,24 @@ class Voila(ExtensionApp):
         None,
         config=True,
         allow_none=True,
-        help=_(
-            'path to notebook to serve with voila'
-        )
+        help=_("path to notebook to serve with voila"),
     )
 
     nbconvert_template_paths = List(
-        [],
-        config=True,
-        help=_(
-            'path to nbconvert templates'
-        )
+        [], config=True, help=_("path to nbconvert templates")
     )
 
     template_paths = List(
-        [],
-        allow_none=True,
-        config=True,
-        help=_(
-            'path to nbconvert templates'
-        )
+        [], allow_none=True, config=True, help=_("path to nbconvert templates")
     )
 
-    static_paths = List(
-        [STATIC_ROOT],
+    static_paths = List([STATIC_ROOT], config=True, help=_("paths to static assets"))
+
+    webbrowser_open_new = Integer(
+        2,
         config=True,
         help=_(
-            'paths to static assets'
-        )
-    )
-
-    webbrowser_open_new = Integer(2, config=True,
-                                  help=_("""Specify Where to open the notebook on startup. This is the
+            """Specify Where to open the notebook on startup. This is the
                                   `new` argument passed to the standard library method `webbrowser.open`.
                                   The behaviour is not guaranteed, but depends on browser support. Valid
                                   values are:
@@ -243,27 +206,30 @@ class Voila(ExtensionApp):
                                   - 1 opens a new window,
                                   - 0 opens in an existing window.
                                   See the `webbrowser.open` documentation for details.
-                                  """))
+                                  """
+        ),
+    )
 
-    custom_display_url = Unicode(u'', config=True,
-                                 help=_("""Override URL shown to users.
+    custom_display_url = Unicode(
+        u"",
+        config=True,
+        help=_(
+            """Override URL shown to users.
                                  Replace actual URL, including protocol, address, port and base URL,
                                  with the given value when displaying URL to the users. Do not change
                                  the actual connection URL. If authentication token is enabled, the
                                  token is added to the custom URL automatically.
                                  This option is intended to be used when the URL to display to the user
                                  cannot be determined reliably by the Jupyter notebook server (proxified
-                                 or containerized setups for example)."""))
+                                 or containerized setups for example)."""
+        ),
+    )
 
     config_file_paths = List(
-        Unicode(),
-        config=True,
-        help=_(
-            'Paths to search for voila.(py|json)'
-        )
+        Unicode(), config=True, help=_("Paths to search for voila.(py|json)")
     )
 
-    @default('config_file_paths')
+    @default("config_file_paths")
     def _config_file_paths_default(self):
         return [os.getcwd()] + jupyter_config_path()
 
@@ -271,17 +237,17 @@ def _config_file_paths_default(self):
     @property
     def nbextensions_path(self):
         """The path to look for Javascript notebook extensions"""
-        path = jupyter_path('nbextensions')
+        path = jupyter_path("nbextensions")
         # FIXME: remove IPython nbextensions path after a migration period
         try:
             from IPython.paths import get_ipython_dir
         except ImportError:
             pass
         else:
-            path.append(os.path.join(get_ipython_dir(), 'nbextensions'))
+            path.append(os.path.join(get_ipython_dir(), "nbextensions"))
         return path
 
-    @default('root_dir')
+    @default("root_dir")
     def _default_root_dir(self):
         if self.notebook_path:
             return os.path.dirname(os.path.abspath(self.notebook_path))
@@ -289,7 +255,7 @@ def _default_root_dir(self):
             return getcwd()
 
     default_url = Unicode("/voila", config=True)
-    
+
     def parse_command_line(self, argv=None):
         super(Voila, self).parse_command_line(argv)
         # Catch first argument as notebook path.
@@ -306,19 +272,19 @@ def parse_command_line(self, argv=None):
     def initialize_server(argv=[], load_other_extensions=False, **kwargs):
         """Get an instance of the Jupyter Server."""
         config = {
-            'ServerApp': {
-                'MappingKernelManager': {
-                    'allowed_message_types': [
-                        'comm_msg',
-                        'comm_info_request',
-                        'kernel_info_request',
-                        'shutdown_request'
+            "ServerApp": {
+                "MappingKernelManager": {
+                    "allowed_message_types": [
+                        "comm_msg",
+                        "comm_info_request",
+                        "kernel_info_request",
+                        "shutdown_request",
                     ]
                 }
             }
         }
         return ExtensionApp.initialize_server(
-            argv=argv, 
+            argv=argv,
             load_other_extensions=load_other_extensions,
             config=Config(config),
             **kwargs
@@ -328,10 +294,7 @@ def initialize_settings(self):
         # Ensure the server finds both serverconfig and nbconfig.
         paths = self.serverapp.config_manager.read_config_path
         for p in jupyter_config_path():
-            paths.extend([
-                os.path.join(p, 'serverconfig'),
-                os.path.join(p, 'nbconfig')
-            ])
+            paths.extend([os.path.join(p, "serverconfig"), os.path.join(p, "nbconfig")])
         # Keep unique paths.
         paths = list(set(paths))
         self.serverapp.config_manager.read_config_path = paths
@@ -340,7 +303,7 @@ def initialize_settings(self):
         # self.serverapp.root_dir = self.root_dir
 
         # Pass notebook path to settings.
-        self.settings.update({ 'notebook_path': self.notebook_path })
+        self.settings.update({"notebook_path": self.notebook_path})
 
     def initialize_templates(self):
         if self.template:
@@ -349,21 +312,32 @@ def initialize_templates(self):
                 self.nbconvert_template_paths,
                 self.static_paths,
                 self.template_paths,
-                self.template
+                self.template,
             )
 
-        self.serverapp.log.debug('using template: %s', self.template)
-        self.serverapp.log.debug('nbconvert template paths:\n\t%s', '\n\t'.join(self.nbconvert_template_paths))
-        self.serverapp.log.debug('template paths:\n\t%s', '\n\t'.join(self.template_paths))
-        self.serverapp.log.debug('static paths:\n\t%s', '\n\t'.join(self.static_paths))
+        self.serverapp.log.debug("using template: %s", self.template)
+        self.serverapp.log.debug(
+            "nbconvert template paths:\n\t%s",
+            "\n\t".join(self.nbconvert_template_paths),
+        )
+        self.serverapp.log.debug(
+            "template paths:\n\t%s", "\n\t".join(self.template_paths)
+        )
+        self.serverapp.log.debug("static paths:\n\t%s", "\n\t".join(self.static_paths))
 
         jenv_opt = {"autoescape": True}
-        env = jinja2.Environment(loader=jinja2.FileSystemLoader(self.template_paths), extensions=['jinja2.ext.i18n'], **jenv_opt)
+        env = jinja2.Environment(
+            loader=jinja2.FileSystemLoader(self.template_paths),
+            extensions=["jinja2.ext.i18n"],
+            **jenv_opt
+        )
 
-        nbui = gettext.translation('nbui', localedir=os.path.join(ROOT, 'i18n'), fallback=True)
+        nbui = gettext.translation(
+            "nbui", localedir=os.path.join(ROOT, "i18n"), fallback=True
+        )
         env.install_gettext_translations(nbui, newstyle=False)
 
-        template_settings = {'voila_jinja2_env': env}
+        template_settings = {"voila_jinja2_env": env}
         self.settings.update(**template_settings)
 
     def initialize_handlers(self):
@@ -371,35 +345,33 @@ def initialize_handlers(self):
         if self.enable_nbextensions:
             self.handlers.append(
                 (
-                    '/voila/nbextensions/(.*)', 
+                    "/voila/nbextensions/(.*)",
                     FileFindHandler,
-                    {
-                        'path': self.nbextensions_path,
-                        'no_cache_paths': ['/']
-                    }
+                    {"path": self.nbextensions_path, "no_cache_paths": ["/"]},
                 )
             )
 
         self.handlers.append(
             (
-                '/voila/files/(.*)', 
+                "/voila/files/(.*)",
                 WhiteListFileHandler,
                 {
-                    'whitelist': self.file_whitelist,
-                    'blacklist': self.file_blacklist,
-                    'path': self.root_dir,
-                }
+                    "whitelist": self.file_whitelist,
+                    "blacklist": self.file_blacklist,
+                    "path": self.root_dir,
+                },
             )
         )
-        
+
         if self.notebook_path:
-            self.handlers.append(('/voila', VoilaHandler))
+            self.handlers.append(("/voila", VoilaHandler))
         else:
             handlers = [
-                ('/voila/render' + path_regex, VoilaHandler),
-                ('/voila', VoilaTreeHandler),
-                ('/voila/tree' + path_regex, VoilaTreeHandler),
+                ("/voila/render" + path_regex, VoilaHandler),
+                ("/voila", VoilaTreeHandler),
+                ("/voila/tree" + path_regex, VoilaTreeHandler),
             ]
             self.handlers.extend(handlers)
 
+
 main = Voila.launch_instance
diff --git a/voila/handler.py b/voila/handler.py
index 121eec7a8..58159c5d4 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -16,7 +16,6 @@
 from jupyter_server.extension.handler import ExtensionHandler
 from jupyter_server.config_manager import recursive_update
 from nbconvert.preprocessors import ClearOutputPreprocessor
-import nbformat
 
 from .execute import executenb, VoilaExecutePreprocessor
 from .exporter import VoilaExporter
@@ -25,24 +24,25 @@
 # Filter for empty cells.
 def filter_empty_code_cells(cell, exporter):
     return (
-        cell.cell_type != 'code' or                     # keep non-code cells
-        (cell.outputs and not exporter.exclude_output)  # keep cell if output not excluded and not empty
-        or not exporter.exclude_input                   # keep cell if input not excluded
+        cell.cell_type != "code"
+        or (  # keep non-code cells
+            cell.outputs and not exporter.exclude_output
+        )  # keep cell if output not excluded and not empty
+        or not exporter.exclude_input  # keep cell if input not excluded
     )
 
 
 class VoilaHandler(ExtensionHandler):
-
     def initialize(self, **kwargs):
         self.kernel_started = False
         super(VoilaHandler, self).initialize(**kwargs)
 
     @property
     def notebook_path(self):
-        path = self.settings.get('notebook_path', None)
+        path = self.settings.get("notebook_path", None)
         # Get relative path to notebook.
         if path is not None:
-            path = os.path.relpath(path, self.config['root_dir'])
+            path = os.path.relpath(path, self.config["root_dir"])
         return path
 
     @tornado.web.authenticated
@@ -50,21 +50,25 @@ def notebook_path(self):
     def get(self, path=None):
         # if the handler got a notebook_path argument, always serve that
         notebook_path = self.notebook_path or path
-        if self.notebook_path and path:  # when we are in single notebook mode but have a path
+        if (
+            self.notebook_path and path
+        ):  # when we are in single notebook mode but have a path
             self.redirect_to_file(path)
             return
 
         if self.config.enable_nbextensions:
             # generate a list of nbextensions that are enabled for the classical notebook
             # a template can use that to load classical notebook extensions, but does not have to
-            notebook_config = self.config_manager.get('notebook')
+            notebook_config = self.config_manager.get("notebook")
             # except for the widget extension itself, since voila has its own
-            load_extensions = notebook_config.get('load_extensions', {})
-            if 'jupyter-js-widgets/extension' in load_extensions:
-                load_extensions['jupyter-js-widgets/extension'] = False
-            if 'voila/extension' in load_extensions:
-                load_extensions['voila/extension'] = False
-            nbextensions = [name for name, enabled in load_extensions.items() if enabled]
+            load_extensions = notebook_config.get("load_extensions", {})
+            if "jupyter-js-widgets/extension" in load_extensions:
+                load_extensions["jupyter-js-widgets/extension"] = False
+            if "voila/extension" in load_extensions:
+                load_extensions["voila/extension"] = False
+            nbextensions = [
+                name for name, enabled in load_extensions.items() if enabled
+            ]
         else:
             nbextensions = []
 
@@ -74,15 +78,21 @@ def get(self, path=None):
         self.cwd = os.path.dirname(notebook_path)
 
         # Launch kernel and execute notebook
-        kernel_id = yield tornado.gen.maybe_future(self.kernel_manager.start_kernel(kernel_name=self.notebook.metadata.kernelspec.name, path=self.cwd))
+        kernel_id = yield tornado.gen.maybe_future(
+            self.kernel_manager.start_kernel(
+                kernel_name=self.notebook.metadata.kernelspec.name, path=self.cwd
+            )
+        )
         km = self.kernel_manager.get_kernel(kernel_id)
-        result = executenb(self.notebook, km=km, cwd=self.cwd, config=self.server_config)
+        executenb(
+            self.notebook, km=km, cwd=self.cwd, config=self.server_config
+        )
 
         # render notebook to html
         resources = {
-            'base_url': self.base_url,
-            'nbextensions': nbextensions,
-            'theme': self.config.theme
+            "base_url": self.base_url,
+            "nbextensions": nbextensions,
+            "theme": self.config.theme,
         }
 
         # include potential extra resources
@@ -93,7 +103,7 @@ def get(self, path=None):
         self.exporter = VoilaExporter(
             template_path=self.config.nbconvert_template_paths,
             config=self.server_config,
-            contents_manager=self.contents_manager  # for the image inlining
+            contents_manager=self.contents_manager,  # for the image inlining
         )
         if self.config.strip_sources:
             self.exporter.exclude_input = True
@@ -106,35 +116,45 @@ def get(self, path=None):
         # or cell_generator to implement progressive cell rendering
         extra_context = {
             # NOTE: we can remove the lambda is we use jinja's async feature, which will automatically await the future
-            'kernel_start': lambda: self._jinja_kernel_start().result(),  # pass the result (not the future) to the template
-            'cell_generator': self._jinja_cell_generator,
-            'notebook_execute': self._jinja_notebook_execute,
+            "kernel_start": lambda: self._jinja_kernel_start().result(),  # pass the result (not the future) to the template
+            "cell_generator": self._jinja_cell_generator,
+            "notebook_execute": self._jinja_notebook_execute,
         }
 
         # Compose reply
-        self.set_header('Content-Type', 'text/html')
+        self.set_header("Content-Type", "text/html")
         # render notebook in snippets, and flush them out to the browser can render progresssively
-        for html_snippet, resources in self.exporter.generate_from_notebook_node(self.notebook, resources=resources, extra_context=extra_context):
+        for html_snippet, resources in self.exporter.generate_from_notebook_node(
+            self.notebook, resources=resources, extra_context=extra_context
+        ):
             self.write(html_snippet)
             self.flush()  # we may not want to consider not flusing after each snippet, but add an explicit flush function to the jinja context
             yield  # give control back to tornado's IO loop, so it can handle static files or other requests
         self.flush()
 
     def redirect_to_file(self, path):
-        self.redirect(url_path_join(self.base_url, 'voila', 'files', path))
+        self.redirect(url_path_join(self.base_url, "voila", "files", path))
 
     @tornado.gen.coroutine
     def _jinja_kernel_start(self):
         assert not self.kernel_started, "kernel was already started"
         # Launch kernel
-        kernel_id = yield tornado.gen.maybe_future(self.kernel_manager.start_kernel(kernel_name=self.notebook.metadata.kernelspec.name, path=self.cwd))
+        kernel_id = yield tornado.gen.maybe_future(
+            self.kernel_manager.start_kernel(
+                kernel_name=self.notebook.metadata.kernelspec.name, path=self.cwd
+            )
+        )
         self.kernel_started = True
         raise tornado.gen.Return(kernel_id)
 
     def _jinja_notebook_execute(self, nb, kernel_id):
         km = self.kernel_manager.get_kernel(kernel_id)
         result = executenb(nb, km=km, cwd=self.cwd, config=self.server_config)
-        result.cells = list(filter(lambda cell: filter_empty_code_cells(cell, self.exporter), result.cells))
+        result.cells = list(
+            filter(
+                lambda cell: filter_empty_code_cells(cell, self.exporter), result.cells
+            )
+        )
         # we modify the notebook in place, since the nb variable cannot be reassigned it seems in jinja2
         # e.g. if we do {% with nb = notebook_execute(nb, kernel_id) %}, the base template/blocks will not
         # see the updated variable (it seems to be local to our block)
@@ -156,11 +176,11 @@ def _jinja_cell_generator(self, nb, kernel_id):
     @tornado.gen.coroutine
     def load_notebook(self, path):
         model = self.contents_manager.get(path=path)
-        if 'content' not in model:
-            raise tornado.web.HTTPError(404, 'file not found')
-        __, extension = os.path.splitext(model.get('path', ''))
-        if model.get('type') == 'notebook':
-            notebook = model['content']
+        if "content" not in model:
+            raise tornado.web.HTTPError(404, "file not found")
+        __, extension = os.path.splitext(model.get("path", ""))
+        if model.get("type") == "notebook":
+            notebook = model["content"]
             notebook = yield self.fix_notebook(notebook)
             raise tornado.gen.Return(notebook)  # TODO py2: replace by return
         elif extension in self.config.extension_language_mapping:
@@ -179,37 +199,53 @@ def fix_notebook(self, notebook):
         """
 
         # Fetch kernel name from the notebook metadata
-        if 'kernelspec' not in notebook.metadata:
+        if "kernelspec" not in notebook.metadata:
             notebook.metadata.kernelspec = nbformat.NotebookNode()
         kernelspec = notebook.metadata.kernelspec
-        kernel_name = kernelspec.get('name', self.kernel_manager.default_kernel_name)
+        kernel_name = kernelspec.get("name", self.kernel_manager.default_kernel_name)
         # We use `maybe_future` to support RemoteKernelSpecManager
-        all_kernel_specs = yield tornado.gen.maybe_future(self.kernel_spec_manager.get_all_specs())
+        all_kernel_specs = yield tornado.gen.maybe_future(
+            self.kernel_spec_manager.get_all_specs()
+        )
         # Find a spec matching the language if the kernel name does not exist in the kernelspecs
         if kernel_name not in all_kernel_specs:
             missing_kernel_name = kernel_name
-            kernel_name = yield self.find_kernel_name_for_language(kernelspec.language.lower(), kernel_specs=all_kernel_specs)
-            self.log.warning('Could not find a kernel named %r, will use  %r', missing_kernel_name, kernel_name)
+            kernel_name = yield self.find_kernel_name_for_language(
+                kernelspec.language.lower(), kernel_specs=all_kernel_specs
+            )
+            self.log.warning(
+                "Could not find a kernel named %r, will use  %r",
+                missing_kernel_name,
+                kernel_name,
+            )
         # We make sure the notebook's kernelspec is correct
         notebook.metadata.kernelspec.name = kernel_name
-        notebook.metadata.kernelspec.display_name = all_kernel_specs[kernel_name]['spec']['display_name']
-        notebook.metadata.kernelspec.language = all_kernel_specs[kernel_name]['spec']['language']
+        notebook.metadata.kernelspec.display_name = all_kernel_specs[kernel_name][
+            "spec"
+        ]["display_name"]
+        notebook.metadata.kernelspec.language = all_kernel_specs[kernel_name]["spec"][
+            "language"
+        ]
         raise tornado.gen.Return(notebook)  # TODO py2: replace by return
 
     @tornado.gen.coroutine
     def create_notebook(self, model, language):
-        all_kernel_specs = yield tornado.gen.maybe_future(self.kernel_spec_manager.get_all_specs())
-        kernel_name = yield self.find_kernel_name_for_language(language, kernel_specs=all_kernel_specs)
+        all_kernel_specs = yield tornado.gen.maybe_future(
+            self.kernel_spec_manager.get_all_specs()
+        )
+        kernel_name = yield self.find_kernel_name_for_language(
+            language, kernel_specs=all_kernel_specs
+        )
         spec = all_kernel_specs[kernel_name]
         notebook = nbformat.v4.new_notebook(
             metadata={
-                'kernelspec': {
-                    'display_name': spec['spec']['display_name'],
-                    'language': spec['spec']['language'],
-                    'name': kernel_name
+                "kernelspec": {
+                    "display_name": spec["spec"]["display_name"],
+                    "language": spec["spec"]["language"],
+                    "name": kernel_name,
                 }
             },
-            cells=[nbformat.v4.new_code_cell(model['content'])],
+            cells=[nbformat.v4.new_code_cell(model["content"])],
         )
         raise tornado.gen.Return(notebook)  # TODO py2: replace by return
 
@@ -220,11 +256,16 @@ def find_kernel_name_for_language(self, kernel_language, kernel_specs=None):
         If multiple kernels matches are found, we try to return the same kernel name each time.
         """
         if kernel_language in self.config.language_kernel_mapping:
-            raise tornado.gen.Return(self.config.language_kernel_mapping[kernel_language])  # TODO py2: replace by return
+            raise tornado.gen.Return(
+                self.config.language_kernel_mapping[kernel_language]
+            )  # TODO py2: replace by return
         if kernel_specs is None:
-            kernel_specs = yield tornado.gen.maybe_future(self.kernel_spec_manager.get_all_specs())
+            kernel_specs = yield tornado.gen.maybe_future(
+                self.kernel_spec_manager.get_all_specs()
+            )
         matches = [
-            name for name, kernel in kernel_specs.items()
+            name
+            for name, kernel in kernel_specs.items()
             if kernel["spec"]["language"].lower() == kernel_language.lower()
         ]
         if matches:
@@ -232,4 +273,6 @@ def find_kernel_name_for_language(self, kernel_language, kernel_specs=None):
             matches.sort(key=lambda name: kernel_specs[name]["spec"]["display_name"])
             raise tornado.gen.Return(matches[0])  # TODO py2: replace by return
         else:
-            raise tornado.web.HTTPError(500, 'No Jupyter kernel for language %r found' % kernel_language)
+            raise tornado.web.HTTPError(
+                500, "No Jupyter kernel for language %r found" % kernel_language
+            )
diff --git a/voila/static_file_handler.py b/voila/static_file_handler.py
index b8e1e63ab..76eb6729b 100644
--- a/voila/static_file_handler.py
+++ b/voila/static_file_handler.py
@@ -33,7 +33,7 @@ def initialize(self, paths, default_filename=None):
     def get_absolute_path(self, root, path):
         # find the first absolute path that exists
         self.root = self.roots[0]
-        for root in self.roots: 
+        for root in self.roots:
             abspath = os.path.abspath(os.path.join(root, path))
             if os.path.exists(abspath):
                 self.root = root  # make sure all the other methods in the base class know how to find the file

From 1b58ece1965806421c6b3f2ffa459beb8d3899f9 Mon Sep 17 00:00:00 2001
From: Zsailer <zachsailer@gmail.com>
Date: Fri, 13 Sep 2019 11:15:27 -0700
Subject: [PATCH 13/22] get notebook_path from serverapp's file_to_run

---
 voila/app.py | 16 ++++------------
 1 file changed, 4 insertions(+), 12 deletions(-)

diff --git a/voila/app.py b/voila/app.py
index 546797cf8..08502aae2 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -184,6 +184,10 @@ class Voila(ExtensionApp):
         help=_("path to notebook to serve with voila"),
     )
 
+    @default('notebook_path')
+    def _default_notebook_path(self):
+        return self.serverapp.file_to_run
+
     nbconvert_template_paths = List(
         [], config=True, help=_("path to nbconvert templates")
     )
@@ -256,18 +260,6 @@ def _default_root_dir(self):
 
     default_url = Unicode("/voila", config=True)
 
-    def parse_command_line(self, argv=None):
-        super(Voila, self).parse_command_line(argv)
-        # Catch first argument as notebook path.
-        if self.extra_args:
-            notebook_path = self.extra_args[0]
-            f = os.path.abspath(notebook_path)
-            self.argv.remove(notebook_path)
-            if not os.path.exists(f):
-                self.log.critical(_("No such file or directory: %s"), f)
-                self.exit(1)
-            self.notebook_path = notebook_path
-
     @staticmethod
     def initialize_server(argv=[], load_other_extensions=False, **kwargs):
         """Get an instance of the Jupyter Server."""

From 347dc6c8b214aa51022f3197ca56a1d9da5e780c Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 11:11:01 +0200
Subject: [PATCH 14/22] fix nbextensions

---
 .../voila/templates/default/nbconvert_templates/base.tpl | 4 ++--
 voila/app.py                                             | 9 ++++++---
 2 files changed, 8 insertions(+), 5 deletions(-)

diff --git a/share/jupyter/voila/templates/default/nbconvert_templates/base.tpl b/share/jupyter/voila/templates/default/nbconvert_templates/base.tpl
index 7580b6801..997d2b7f9 100644
--- a/share/jupyter/voila/templates/default/nbconvert_templates/base.tpl
+++ b/share/jupyter/voila/templates/default/nbconvert_templates/base.tpl
@@ -49,7 +49,7 @@
 {% block footer %}
 {% block footer_js %}
 <script>
-requirejs.config({
+requirejs.config({ 
     baseUrl: '{{resources.base_url}}static/voila/',
     waitSeconds: 30
 })
@@ -57,7 +57,7 @@ requirejs(
     [
         "main",
     {% for ext in resources.nbextensions -%}
-        "{{resources.base_url}}voila/nbextensions/{{ ext }}.js",
+        "{{resources.base_url}}static/voila/nbextensions/{{ ext }}.js",
     {% endfor %}
     ]
 )
diff --git a/voila/app.py b/voila/app.py
index 08502aae2..9f90b4b45 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -335,12 +335,15 @@ def initialize_templates(self):
     def initialize_handlers(self):
         # Serving notebook extensions
         if self.enable_nbextensions:
-            self.handlers.append(
+            # Note, this handler 'overlaps' with the "/static/voila" handler that our base
+            # class adds. Since this regex is more specific, and added first, we're all good.
+            self.handlers.insert(
+                0,
                 (
-                    "/voila/nbextensions/(.*)",
+                    "static/voila/nbextensions/(.*)",
                     FileFindHandler,
                     {"path": self.nbextensions_path, "no_cache_paths": ["/"]},
-                )
+                ),
             )
 
         self.handlers.append(

From 64e8338d3648a53c9b6726f67f9a1469bacfd6c6 Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 12:25:11 +0200
Subject: [PATCH 15/22] fix execute test

---
 tests/app/conftest.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 482166b8b..4d5fe2b3b 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -35,12 +35,12 @@ def voila_args(voila_notebook, voila_args_extra, voila_config_file_paths_arg):
 
 
 @pytest.fixture
-def voila_app(server_config, voila_args, voila_config):
+def voila_app(server_config, voila_config, voila_args):
     # Get an instance of Voila
     voila_app = Voila(**voila_config)
     # Get an instance of the underlying server. This is
     # configured automatically when launched by command line.
-    serverapp = voila_app.initialize_server(**server_config)
+    serverapp = voila_app.initialize_server(voila_args, **server_config)
     # silence the start method for pytests.
     serverapp.start = lambda self: None
     voila_app.initialize(serverapp, argv=voila_args)

From e0cec484ca3fcb3460471be0b21d11c8da8a37f9 Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 14:18:16 +0200
Subject: [PATCH 16/22] fix: treat notebook_path as truthy

---
 voila/handler.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/voila/handler.py b/voila/handler.py
index 58159c5d4..15b913090 100644
--- a/voila/handler.py
+++ b/voila/handler.py
@@ -39,9 +39,9 @@ def initialize(self, **kwargs):
 
     @property
     def notebook_path(self):
-        path = self.settings.get("notebook_path", None)
+        path = self.settings.get("notebook_path")
         # Get relative path to notebook.
-        if path is not None:
+        if path:  # path can be '', which is the default of ServerApp.file_to_run
             path = os.path.relpath(path, self.config["root_dir"])
         return path
 

From fbb2e867c6f909ea14c474d692c6eb18f51a8d0c Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 14:18:37 +0200
Subject: [PATCH 17/22] fix tests

---
 tests/app/conftest.py        | 1 +
 tests/app/cwd_subdir_test.py | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 4d5fe2b3b..226286e3a 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -45,6 +45,7 @@ def voila_app(server_config, voila_config, voila_args):
     serverapp.start = lambda self: None
     voila_app.initialize(serverapp, argv=voila_args)
     yield voila_app
+    serverapp.clear_instance()
 
 
 @pytest.fixture
diff --git a/tests/app/cwd_subdir_test.py b/tests/app/cwd_subdir_test.py
index 881790c2c..08c60fb32 100644
--- a/tests/app/cwd_subdir_test.py
+++ b/tests/app/cwd_subdir_test.py
@@ -10,7 +10,7 @@ def cwd_subdir_notebook_url(base_url):
 @pytest.fixture
 def voila_args(notebook_directory, voila_args_extra):
     return [
-        "--Voila.root_dir=%r" % notebook_directory,
+        "--ServerApp.root_dir=%r" % notebook_directory,
         "--Voila.log_level=DEBUG",
     ] + voila_args_extra
 

From d0b5ba0e66f23cf5bee09edf7b08fe0649bbc8e5 Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 14:57:21 +0200
Subject: [PATCH 18/22] install master jupyter server

---
 .travis.yml | 2 ++
 setup.py    | 2 +-
 2 files changed, 3 insertions(+), 1 deletion(-)

diff --git a/.travis.yml b/.travis.yml
index 7da471691..c7b522cfc 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -20,6 +20,8 @@ before_install:
   - conda info -a
   - conda create -q -n test-environment -c conda-forge python=$PYTHON_VERSION jupyter_server==0.1.0 jupyterlab_pygments==0.1.0 pytest==3.10.1 nbconvert=5.6 pytest-cov nodejs flake8 ipywidgets matplotlib xeus-cling
   - source activate test-environment
+  - pip uninstall jupyter_server -y
+  - pip install git+https://github.com/jupyter/jupyter_server@master
 install:
   - pip install ".[test]"
   - cd tests/test_template; pip install .; cd ../../;
diff --git a/setup.py b/setup.py
index e615a1d95..5039a90df 100644
--- a/setup.py
+++ b/setup.py
@@ -375,7 +375,7 @@ def get_data_files():
         ]
     },
     'install_requires': [
-        'jupyter_server>=0.1.0,<0.2.0',
+        'jupyter_server>=0.2.0.dev0,<0.3.0',
         'nbconvert>=5.6.0,<6',
         'jupyterlab_pygments>=0.1.0,<0.2',
         'pygments>=2.4.1,<3'  # Explicitly requiring pygments which is a second-order dependency.

From cc4a97e6ffcb81dc5ea5a1e5b2435e9449395a7a Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 15:25:53 +0200
Subject: [PATCH 19/22] chore(ci): drop py27 testing, add py35

---
 .travis.yml | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index c7b522cfc..290904cc1 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -4,7 +4,7 @@ os:
  - osx
 env:
  matrix:
-  - PYTHON_VERSION=2.7
+  - PYTHON_VERSION=3.5
   - PYTHON_VERSION=3.6
   - PYTHON_VERSION=3.7
 before_install:
@@ -18,7 +18,7 @@ before_install:
   - conda config --set always_yes yes --set changeps1 no
   - conda update -q conda
   - conda info -a
-  - conda create -q -n test-environment -c conda-forge python=$PYTHON_VERSION jupyter_server==0.1.0 jupyterlab_pygments==0.1.0 pytest==3.10.1 nbconvert=5.6 pytest-cov nodejs flake8 ipywidgets matplotlib xeus-cling
+  - conda create -q -n test-environment -c conda-forge python=$PYTHON_VERSION nodejs flake8 xeus-cling
   - source activate test-environment
   - pip uninstall jupyter_server -y
   - pip install git+https://github.com/jupyter/jupyter_server@master

From cad9b759884a3424399aa2fc94a7196abddfe963 Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 15:49:08 +0200
Subject: [PATCH 20/22] chore(cmd): add voila as console_script entry point

---
 setup.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/setup.py b/setup.py
index 5039a90df..6720c34a3 100644
--- a/setup.py
+++ b/setup.py
@@ -371,7 +371,8 @@ def get_data_files():
     },
     'entry_points': {
         'console_scripts': [
-            'jupyter-voila = voila.app:main'
+            'jupyter-voila = voila.app:main',
+            'voila = voila.app:main'
         ]
     },
     'install_requires': [

From 7d99b418ada8887d2bd4c5592bfd3e3989dda145 Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 15:49:35 +0200
Subject: [PATCH 21/22] fix: --help needed reference to ServerApp

---
 voila/app.py | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/voila/app.py b/voila/app.py
index 9f90b4b45..c27b9e211 100644
--- a/voila/app.py
+++ b/voila/app.py
@@ -21,6 +21,7 @@
 from jupyter_server.base.handlers import path_regex
 from jupyter_server.base.handlers import FileFindHandler
 from jupyter_server.extension.application import ExtensionApp
+from jupyter_server.serverapp import ServerApp
 from jupyter_core.paths import jupyter_config_path, jupyter_path
 
 from ipython_genutils.py3compat import getcwd
@@ -104,7 +105,7 @@ class Voila(ExtensionApp):
         "enable_nbextensions": "Voila.enable_nbextensions",
     }
 
-    classes = [VoilaExecutePreprocessor, VoilaExporter, VoilaCSSPreprocessor]
+    classes = [VoilaExecutePreprocessor, VoilaExporter, VoilaCSSPreprocessor, ServerApp]
 
     template = Unicode(
         "default",

From cb6c68939fe24288043b95112774b846b52cbc86 Mon Sep 17 00:00:00 2001
From: "Maarten A. Breddels" <maartenbreddels@gmail.com>
Date: Mon, 21 Oct 2019 17:32:28 +0200
Subject: [PATCH 22/22] Put back solution to #231, similar to #242

---
 tests/app/conftest.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/tests/app/conftest.py b/tests/app/conftest.py
index 226286e3a..b9e33d3b5 100644
--- a/tests/app/conftest.py
+++ b/tests/app/conftest.py
@@ -45,6 +45,7 @@ def voila_app(server_config, voila_config, voila_args):
     serverapp.start = lambda self: None
     voila_app.initialize(serverapp, argv=voila_args)
     yield voila_app
+    serverapp.cleanup_kernels()
     serverapp.clear_instance()