Issue 1619 conftest assert rewrite

AUTHORS

@@ -84,6 +84,7 @@ Ronny Pfannschmidt
 Ross Lawley
 Ryan Wooden
 Samuele Pedroni
+Stephan Obermann
 Tareq Alayan
 Tom Viner
 Trevor Bekolay

CHANGELOG.rst

@@ -74,15 +74,27 @@
   message to raise when no exception occurred.
   Thanks `@palaviv`_ for the complete PR (`#1616`_).
 
+* ``conftest.py`` files now benefit from assertion rewriting; previously it
+  was only available for test modules. Thanks `@flub`_, `@sober7`_ and
+  `@nicoddemus`_ for the PR (`#1619`_).
+
+*
+
+*
+
+*
+
 .. _@milliams: https://github.com/milliams
 .. _@csaftoiu: https://github.com/csaftoiu
+.. _@flub: https://github.com/flub
 .. _@novas0x2a: https://github.com/novas0x2a
 .. _@kalekundert: https://github.com/kalekundert
 .. _@tareqalayan: https://github.com/tareqalayan
 .. _@ceridwen: https://github.com/ceridwen
 .. _@palaviv: https://github.com/palaviv
 .. _@omarkohl: https://github.com/omarkohl
 .. _@mikofski: https://github.com/mikofski
+.. _@sober7: https://github.com/sober7
 
 .. _#1426: https://github.com/pytest-dev/pytest/issues/1426
 .. _#1428: https://github.com/pytest-dev/pytest/pull/1428
@@ -95,6 +107,7 @@
 .. _#1474: https://github.com/pytest-dev/pytest/pull/1474
 .. _#1502: https://github.com/pytest-dev/pytest/pull/1502
 .. _#1520: https://github.com/pytest-dev/pytest/pull/1520
+.. _#1619: https://github.com/pytest-dev/pytest/issues/1619
 .. _#372: https://github.com/pytest-dev/pytest/issues/372
 .. _#1544: https://github.com/pytest-dev/pytest/issues/1544
 .. _#1616: https://github.com/pytest-dev/pytest/pull/1616

_pytest/assertion/__init__.py

@@ -4,6 +4,8 @@
 import py
 import os
 import sys
+
+from _pytest.config import hookimpl
 from _pytest.monkeypatch import monkeypatch
 from _pytest.assertion import util
 
@@ -42,9 +44,13 @@ def __init__(self, config, mode):
         self.trace = config.trace.root.get("assertion")
 
 
-def pytest_configure(config):
-    mode = config.getvalue("assertmode")
-    if config.getvalue("noassert") or config.getvalue("nomagic"):
+@hookimpl(tryfirst=True)
+def pytest_load_initial_conftests(early_config, parser, args):
+    ns, ns_unknown_args = parser.parse_known_and_unknown_args(args)
+    mode = ns.assertmode
+    no_assert = ns.noassert
+    no_magic = ns.nomagic
+    if no_assert or no_magic:
         mode = "plain"
     if mode == "rewrite":
         try:
@@ -57,25 +63,29 @@ def pytest_configure(config):
             if (sys.platform.startswith('java') or
                     sys.version_info[:3] == (2, 6, 0)):
                 mode = "reinterp"
+
+    early_config._assertstate = AssertionState(early_config, mode)
+    warn_about_missing_assertion(mode, early_config.pluginmanager)
+
     if mode != "plain":
         _load_modules(mode)
         m = monkeypatch()
-        config._cleanup.append(m.undo)
+        early_config._cleanup.append(m.undo)
         m.setattr(py.builtin.builtins, 'AssertionError',
                   reinterpret.AssertionError)  # noqa
+
     hook = None
     if mode == "rewrite":
-        hook = rewrite.AssertionRewritingHook()  # noqa
+        hook = rewrite.AssertionRewritingHook(early_config)  # noqa
         sys.meta_path.insert(0, hook)
-    warn_about_missing_assertion(mode)
-    config._assertstate = AssertionState(config, mode)
-    config._assertstate.hook = hook
-    config._assertstate.trace("configured with mode set to %r" % (mode,))
+
+    early_config._assertstate.hook = hook
+    early_config._assertstate.trace("configured with mode set to %r" % (mode,))
     def undo():
-        hook = config._assertstate.hook
+        hook = early_config._assertstate.hook
         if hook is not None and hook in sys.meta_path:
             sys.meta_path.remove(hook)
-    config.add_cleanup(undo)
+    early_config.add_cleanup(undo)
 
 
 def pytest_collection(session):
@@ -154,7 +164,8 @@ def _load_modules(mode):
         from _pytest.assertion import rewrite  # noqa
 
 
-def warn_about_missing_assertion(mode):
+def warn_about_missing_assertion(mode, pluginmanager):
+    print('got here')
     try:
         assert False
     except AssertionError:
@@ -166,10 +177,18 @@ def warn_about_missing_assertion(mode):
         else:
             specifically = "failing tests may report as passing"
 
-        sys.stderr.write("WARNING: " + specifically +
-                         " because assert statements are not executed "
-                         "by the underlying Python interpreter "
-                         "(are you using python -O?)\n")
+        # temporarily disable capture so we can print our warning
+        capman = pluginmanager.getplugin('capturemanager')
+        try:
+            out, err = capman.suspendcapture()
+            sys.stderr.write("WARNING: " + specifically +
+                             " because assert statements are not executed "
+                             "by the underlying Python interpreter "
+                             "(are you using python -O?)\n")
+        finally:
+            capman.resumecapture()
+            sys.stdout.write(out)
+            sys.stderr.write(err)
 
 
 # Expose this plugin's implementation for the pytest_assertrepr_compare hook

_pytest/assertion/rewrite.py

@@ -44,20 +44,18 @@
 class AssertionRewritingHook(object):
     """PEP302 Import hook which rewrites asserts."""
 
-    def __init__(self):
+    def __init__(self, config):
+        self.config = config
+        self.fnpats = config.getini("python_files")
         self.session = None
         self.modules = {}
         self._register_with_pkg_resources()
 
     def set_session(self, session):
-        self.fnpats = session.config.getini("python_files")
         self.session = session
 
     def find_module(self, name, path=None):
-        if self.session is None:
-            return None
-        sess = self.session
-        state = sess.config._assertstate
+        state = self.config._assertstate
         state.trace("find_module called for: %s" % name)
         names = name.rsplit(".", 1)
         lastname = names[-1]
@@ -86,24 +84,11 @@ def find_module(self, name, path=None):
                 return None
         else:
             fn = os.path.join(pth, name.rpartition(".")[2] + ".py")
+
         fn_pypath = py.path.local(fn)
-        # Is this a test file?
-        if not sess.isinitpath(fn):
-            # We have to be very careful here because imports in this code can
-            # trigger a cycle.
-            self.session = None
-            try:
-                for pat in self.fnpats:
-                    if fn_pypath.fnmatch(pat):
-                        state.trace("matched test file %r" % (fn,))
-                        break
-                else:
-                    return None
-            finally:
-                self.session = sess
-        else:
-            state.trace("matched test file (was specified on cmdline): %r" %
-                        (fn,))
+        if not self._should_rewrite(fn_pypath, state):
+            return
+
         # The requested module looks like a test file, so rewrite it. This is
         # the most magical part of the process: load the source, rewrite the
         # asserts, and load the rewritten source. We also cache the rewritten
@@ -151,6 +136,32 @@ def find_module(self, name, path=None):
         self.modules[name] = co, pyc
         return self
 
+    def _should_rewrite(self, fn_pypath, state):
+        # always rewrite conftest files
+        fn = str(fn_pypath)
+        if fn_pypath.basename == 'conftest.py':
+            state.trace("rewriting conftest file: %r" % (fn,))
+            return True
+        elif self.session is not None:
+            if self.session.isinitpath(fn):
+                state.trace("matched test file (was specified on cmdline): %r" %
+                            (fn,))
+                return True
+            else:
+                # modules not passed explicitly on the command line are only
+                # rewritten if they match the naming convention for test files
+                session = self.session  # avoid a cycle here
+                self.session = None
+                try:
+                    for pat in self.fnpats:
+                        if fn_pypath.fnmatch(pat):
+                            state.trace("matched test file %r" % (fn,))
+                            return True
+                finally:
+                    self.session = session
+                    del session
+        return False
+
     def load_module(self, name):
         # If there is an existing module object named 'fullname' in
         # sys.modules, the loader must use that existing module. (Otherwise,

testing/test_assertrewrite.py

@@ -694,6 +694,40 @@ def test_foo(self):
         result = testdir.runpytest()
         result.stdout.fnmatch_lines('*1 passed*')
 
+    @pytest.mark.parametrize('initial_conftest', [True, False])
+    @pytest.mark.parametrize('mode', ['plain', 'rewrite', 'reinterp'])
+    def test_conftest_assertion_rewrite(self, testdir, initial_conftest, mode):
+        """Test that conftest files are using assertion rewrite on import.
+        (#1619)
+        """
+        testdir.tmpdir.join('foo/tests').ensure(dir=1)
+        conftest_path = 'conftest.py' if initial_conftest else 'foo/conftest.py'
+        contents = {
+            conftest_path: """
+                import pytest
+                @pytest.fixture
+                def check_first():
+                    def check(values, value):
+                        assert values.pop(0) == value
+                    return check
+            """,
+            'foo/tests/test_foo.py': """
+                def test(check_first):
+                    check_first([10, 30], 30)
+            """
+        }
+        testdir.makepyfile(**contents)
+        result = testdir.runpytest_subprocess('--assert=%s' % mode)
+        if mode == 'plain':
+            expected = 'E       AssertionError'
+        elif mode == 'rewrite':
+            expected = '*assert 10 == 30*'
+        elif mode == 'reinterp':
+            expected = '*AssertionError:*was re-run*'
+        else:
+            assert 0
+        result.stdout.fnmatch_lines([expected])
+
 
 def test_issue731(testdir):
     testdir.makepyfile("""

testing/test_config.py

@@ -485,9 +485,14 @@ def pytest_load_initial_conftests(self):
     pm.register(m)
     hc = pm.hook.pytest_load_initial_conftests
     l = hc._nonwrappers + hc._wrappers
-    assert l[-1].function.__module__ == "_pytest.capture"
-    assert l[-2].function == m.pytest_load_initial_conftests
-    assert l[-3].function.__module__ == "_pytest.config"
+    expected = [
+        "_pytest.config",
+        'test_config',
+        '_pytest.assertion',
+        '_pytest.capture',
+    ]
+    assert [x.function.__module__ for x in l] == expected
+
 
 class TestWarning:
     def test_warn_config(self, testdir):