fix RunwayModule not subscriptable & awacs/troposphere unload causing…

… isinstance inconsistencies (#361)

* fix module not subscriptable

introduced in #354

* exclude awacs and troposphere from cfngin sys.modules unload

bug introduced in #351
resolves #360

* update cfngin test with new call args

* add test for sys_module_exclude

runway/cfngin/cfngin.py

@@ -109,11 +109,13 @@ def deploy(self, force=False, sys_path=None):
             sys_path = self.sys_path
         config_files = self.find_config_files(sys_path=sys_path)
 
-        with SafeHaven(environ=self.__ctx.env_vars):
+        with SafeHaven(environ=self.__ctx.env_vars,
+                       sys_modules_exclude=['awacs', 'troposphere']):
             for config in config_files:
                 ctx = self.load(config)
                 LOGGER.info('%s: deploying...', os.path.basename(config))
-                with SafeHaven(argv=['stacker', 'build', ctx.config_path]):
+                with SafeHaven(argv=['stacker', 'build', ctx.config_path],
+                               sys_modules_exclude=['awacs', 'troposphere']):
                     action = build.Action(
                         context=ctx,
                         provider_builder=self._get_provider_builder(

runway/module/__init__.py

@@ -147,6 +147,18 @@ def destroy(self):
         raise NotImplementedError('You must implement the destroy() method '
                                   'yourself!')
 
+    def __getitem__(self, key):
+        """Make the object subscriptable.
+
+        Args:
+            key (str): Attribute to get.
+
+        Returns:
+            Any
+
+        """
+        return getattr(self, key)
+
 
 class RunwayModuleNpm(RunwayModule):  # pylint: disable=abstract-method
     """Base class for Runway modules that use npm."""

runway/util.py

@@ -297,12 +297,16 @@ class SafeHaven(AbstractContextManager):
     """
 
     # pylint: disable=redefined-outer-name
-    def __init__(self, argv=None, environ=None, sys_path=None):
+    def __init__(self, argv=None, environ=None, sys_modules_exclude=None,
+                 sys_path=None):
         """Instantiate class.
 
         Args:
             argv (Optional[List[str]]): Override the value of sys.argv.
             environ (Optional[Dict[str, str]]): Update os.environ.
+            sys_modules_exclude (Optional[List[str]]): A list of modules to
+                exclude when reverting sys.modules to its previous state.
+                These are checked as ``module.startswith(name)``.
             sys_path (Optional[List[str]]): Override the value of sys.path.
 
         """
@@ -314,6 +318,7 @@ def __init__(self, argv=None, environ=None, sys_path=None):
         self.__sys_path = list(sys.path)
         # more informative origin for log statements
         self.log = logging.getLogger('runway.' + self.__class__.__name__)
+        self.sys_modules_exclude = sys_modules_exclude or []
 
         if isinstance(argv, list):
             sys.argv = argv
@@ -347,7 +352,9 @@ def reset_sys_modules(self):
         # sys.modules can be manipulated to force reloading modules but,
         # replacing it outright does not work as expected
         for module in list(sys.modules.keys()):
-            if module not in self.__sys_modules:
+            if module not in self.__sys_modules and \
+                    not any(module.startswith(n)
+                            for n in self.sys_modules_exclude):
                 self.log.debug('removed sys.module: {"%s": "%s"}', module,
                                sys.modules.pop(module))
 

tests/cfngin/test_cfngin.py

@@ -121,12 +121,15 @@ def test_deploy(self, mock_action, cfngin_fixtures, tmp_path,
                                          {'concurrency': 0,
                                           'tail': False}])
         patch_safehaven.assert_has_calls([
-            call(environ=context.env_vars),
+            call(environ=context.env_vars,
+                 sys_modules_exclude=['awacs', 'troposphere']),
             call.__enter__(),
-            call(argv=['stacker', 'build', str(tmp_path / 'basic.yml')]),
+            call(argv=['stacker', 'build', str(tmp_path / 'basic.yml')],
+                 sys_modules_exclude=['awacs', 'troposphere']),
             call.__enter__(),
             call.__exit__(None, None, None),
-            call(argv=['stacker', 'build', str(tmp_path / 'basic2.yml')]),
+            call(argv=['stacker', 'build', str(tmp_path / 'basic2.yml')],
+                 sys_modules_exclude=['awacs', 'troposphere']),
             call.__enter__(),
             call.__exit__(None, None, None),
             call.__exit__(None, None, None),

tests/test_util.py

@@ -191,6 +191,22 @@ def test_sys_modules(self, caplog, monkeypatch):
         assert caplog.messages[:2] == expected_logs
         assert caplog.messages[-1] == 'leaving the safe haven...'
 
+    def test_sys_modules_exclude(self, monkeypatch):
+        """Test sys.modules interations with excluded module."""
+        monkeypatch.setattr(SafeHaven, 'reset_all', MagicMock())
+
+        module = 'tests.fixtures.mock_hooks'
+
+        assert module not in sys.modules
+        with SafeHaven(sys_modules_exclude=module) as obj:
+            from .fixtures import mock_hooks  # noqa pylint: disable=E,W,C
+            assert module in sys.modules
+            obj.reset_sys_modules()
+        assert module in sys.modules
+        # cleanup
+        del sys.modules[module]
+        assert module not in sys.modules
+
     @pytest.mark.parametrize('provided', TEST_PARAMS)
     def test_sys_path(self, provided, caplog, monkeypatch):
         """Test sys.path interactions."""