Fix handling of pausing fs during reporting

- use hookwrapper to disable patching
  during reporting
- disable patching between tests for non function-scope fixtures

Author: mrbean-bremen

CHANGES.md

@@ -15,6 +15,9 @@ The released versions correspond to PyPI releases.
 
 ## Unreleased
 
+### Fixes
+* fixed an interaction problem of `fs` with other pytest fixtures (see [#1200](../../issues/1200))
+
 ### Infrastructure
 * fixed some warnings in tests (see [#1190](../../issues/1190))
 

docs/usage.rst

@@ -43,6 +43,9 @@ you can define a longer name in your ``conftest.py`` and use that in your tests:
         """
         yield fs
 
+.. note:: Filesystem patching is paused in the pytest logreport phases to ensure that
+  logs are correctly written to the real filesystem.
+
 Class-, module- and session-scoped fixtures
 ...........................................
 For convenience, class-, module- and session-scoped fixtures with the same
@@ -55,6 +58,9 @@ respectively.
   done in the fake filesystem inside a test will remain there until the respective scope
   ends (see also :ref:`nested_patcher_invocation`).
 
+.. note:: To avoid unwanted side-effects, the patching is paused between the tests,
+  even if the fixture is still active.
+
 .. _unittest_usage:
 
 Patch using fake_filesystem_unittest

pyfakefs/fake_filesystem_unittest.py

@@ -789,7 +789,7 @@ def fake_path_module(fs: FakeFilesystem):
             "io": fake_io.FakeIoModule,
             "pathlib": fake_pathlib_module,
         }
-        if sys.version_info >= (3, 13):
+        if sys.version_info[:2] == (3, 13):
             # for Python 3.13, we need both pathlib (path with __init__.py) and
             # pathlib._local (has the actual implementation);
             # depending on how pathlib is imported, either may be used
@@ -806,10 +806,10 @@ def fake_path_module(fs: FakeFilesystem):
         # be contained in - this allows for alternative modules like
         # `pathlib` and `pathlib2`
         self._class_modules["Path"] = ["pathlib"]
-        if sys.version_info >= (3, 13):
+        if sys.version_info[:2] == (3, 13):
             self._class_modules["Path"].append("pathlib._local")
         self._unfaked_module_classes["pathlib"] = fake_pathlib.RealPathlibModule
-        if sys.version_info >= (3, 13):
+        if sys.version_info[:2] == (3, 13):
             self._unfaked_module_classes["pathlib._local"] = (
                 fake_pathlib.RealPathlibModule
             )

pyfakefs/pytest_plugin.py

@@ -9,11 +9,13 @@ def my_fakefs_test(fs):
     assert os.path.exists('/var/data/xx1.txt')
 """
 
+import contextlib
+
 import py
 import pytest
 from _pytest import capture
 
-from pyfakefs.fake_filesystem_unittest import Patcher
+from pyfakefs.fake_filesystem_unittest import Patcher, Pause
 
 try:
     from _pytest import pathlib
@@ -85,22 +87,18 @@ def pytest_sessionfinish(session, exitstatus):
 @pytest.hookimpl(hookwrapper=True, tryfirst=True)
 def pytest_runtest_logreport(report):
     """Make sure that patching is not active during reporting."""
-    pause = Patcher.PATCHER is not None and report.when == "call"
-    if pause:
+    pause = Patcher.PATCHER is not None and Patcher.PATCHER.is_patching
+    context_mgr = Pause(Patcher.PATCHER) if pause else contextlib.nullcontext()
+    with context_mgr:
+        yield
+    if pause and report.when == "teardown":
+        # if we get here, we are not in a function scope fixture
+        # in this case, we still want to pause patching between the tests
         Patcher.PATCHER.pause()
-    yield
 
 
-@pytest.hookimpl(hookwrapper=True, trylast=True)
+@pytest.hookimpl(tryfirst=True)
 def pytest_runtest_setup(item):
+    # resume patcher if not in a function scope
     if Patcher.PATCHER is not None:
         Patcher.PATCHER.resume()
-    yield
-
-
-@pytest.hookimpl(hookwrapper=True, tryfirst=True)
-def pytest_runtest_teardown(item, nextitem):
-    """Make sure that patching is not active during reporting."""
-    if Patcher.PATCHER is not None:
-        Patcher.PATCHER.pause()
-    yield

pyfakefs/pytest_tests/test_fs_with_monkeypatch.py

@@ -0,0 +1,12 @@
+from pyfakefs.fake_filesystem import FakeFileOpen
+
+
+def test_monkeypatch_with_fs(fs, monkeypatch):
+    """Regression test for issue 1200"""
+    fake_open = FakeFileOpen(fs)
+    monkeypatch.setattr("builtins.open", fake_open, raising=False)
+
+
+def test_open():
+    """Tests if open is poisoned by the above test"""
+    assert "built-in" in str(open)