Make sure that pyfakefs is not active during pytest reporting

- pause the patching in pytest_runtest_logreport
- fixes #904

Author: mrbean-bremen

CHANGES.md

@@ -3,6 +3,10 @@ The released versions correspond to PyPI releases.
 
 ## Unreleased
 
+### Fixes
+* fixes the problem that filesystem patching was still active in the pytest
+  logreport phase (see [#904](../../issues/904))
+
 ## [Version 5.3.0](https://pypi.python.org/pypi/pyfakefs/5.3.0) (2023-10-11)
 Adds official support for Python 3.12.
 

pyfakefs/fake_filesystem_unittest.py

@@ -628,6 +628,7 @@ def __init__(
         self._isStale = True
         self._dyn_patcher: Optional[DynamicPatcher] = None
         self._patching = False
+        self._paused = False
 
     @classmethod
     def clear_fs_cache(cls) -> None:
@@ -898,6 +899,7 @@ def setUp(self, doctester: Any = None) -> None:
     def start_patching(self) -> None:
         if not self._patching:
             self._patching = True
+            self._paused = False
 
             self.patch_modules()
             self.patch_functions()
@@ -975,17 +977,22 @@ def tearDown(self, doctester: Any = None):
         else:
             self.__class__.PATCHER = None
 
-    def stop_patching(self) -> None:
+    def stop_patching(self, temporary=False) -> None:
         if self._patching:
             self._isStale = True
             self._patching = False
+            self._paused = temporary
             if self._stubs:
                 self._stubs.smart_unset_all()
             self.unset_defaults()
             if self._dyn_patcher:
                 self._dyn_patcher.cleanup()
                 sys.meta_path.pop(0)
 
+    @property
+    def is_patching(self):
+        return self._patching
+
     def unset_defaults(self) -> None:
         for fct, idx, ft in self.FS_DEFARGS:
             new_defaults = []
@@ -1003,15 +1010,16 @@ def pause(self) -> None:
         Calling pause() twice is silently ignored.
 
         """
-        self.stop_patching()
+        self.stop_patching(temporary=True)
 
     def resume(self) -> None:
         """Resume the patching of the file system modules if `pause` has
         been called before. After that call, all file system calls are
         executed in the fake file system.
         Does nothing if patching is not paused.
         """
-        self.start_patching()
+        if self._paused:
+            self.start_patching()
 
 
 class Pause:

pyfakefs/pytest_plugin.py

@@ -80,3 +80,16 @@ def fs_session(request):
 def pytest_sessionfinish(session, exitstatus):
     """Make sure that the cache is cleared before the final test shutdown."""
     Patcher.clear_fs_cache()
+
+
+@pytest.hookimpl(tryfirst=True)
+def pytest_runtest_logreport(report):
+    """Make sure that patching is not active during reporting."""
+    if report.when == "call" and Patcher.PATCHER is not None:
+        Patcher.PATCHER.pause()
+
+
+def pytest_runtest_call(item):
+    """Resume paused patching before test start."""
+    if Patcher.PATCHER is not None:
+        Patcher.PATCHER.resume()

pyfakefs/pytest_tests/pytest_module_fixture_test.py

@@ -20,7 +20,19 @@ def use_fs(fs_module):
     yield fs_module
 
 
+@pytest.fixture(autouse=True)
+def check_patching_stopped(fs):
+    # patching shall be paused at test end, even in module scope (see #904)
+    yield
+    assert not fs.patcher.is_patching
+
+
 @pytest.mark.usefixtures("fs")
-def test_fs_uses_fs_module():
+def test_fs_uses_fs_module1():
     # check that `fs` uses the same filesystem as `fs_module`
     assert os.path.exists(os.path.join("foo", "bar"))
+
+
+def test_fs_uses_fs_module2(fs):
+    # check that testing was not stopped by the first test
+    assert os.path.exists(os.path.join("foo", "bar"))