Autouse-pytester in test_pathlib

testing/test_pathlib.py

@@ -37,6 +37,20 @@
 import pytest
 
 
+@pytest.fixture(autouse=True)
+def autouse_pytester(pytester: Pytester) -> None:
+    """
+    Fixture to make pytester() being autouse for all tests in this module.
+
+    pytester makes sure to restore sys.path to its previous state, and many tests in this module
+    import modules and change sys.path because of that, so common module names such as "test" or "test.conftest"
+    end up leaking to tests in other modules.
+
+    Note: we might consider extracting the sys.path restoration aspect into its own fixture, and apply it
+    to the entire test suite always.
+    """
+
+
 class TestFNMatcherPort:
     """Test our port of py.common.FNMatcher (fnmatch_ex)."""