Skip symlink sibling test on Windows without symlink support #13771

Author: Mulat Mekonen

AUTHORS

@@ -320,6 +320,7 @@ Mike Hoyle (hoylemd)
 Mike Lundy
 Milan Lesnek
 Miro Hrončok
+Mulat Mekonen
 mrbean-bremen
 Nathan Goldbaum
 Nathan Rousseau

changelog/13771.bugfix.rst

@@ -0,0 +1 @@
+Skip `test_do_not_collect_symlink_siblings` on Windows environments without symlink support to avoid false negatives.

testing/test_collection.py

@@ -1860,27 +1860,41 @@ def test_pyargs_collection_tree(pytester: Pytester, monkeypatch: MonkeyPatch) ->
     )
 
 
+def _can_create_symlink(base: Path) -> bool:
+    """Check if the current environment supports creating symlinks."""
+    target = base / "target"
+    link = base / "link"
+    try:
+        if target.exists():
+            target.rmdir()  # remove old one if exists
+        target.mkdir()
+
+        if link.exists() or link.is_symlink():
+            link.unlink()
+        os.symlink(target, link, target_is_directory=True)
+        return link.is_symlink()
+    except (OSError, NotImplementedError):
+        return False
+
+
+@pytest.mark.skipif(
+    sys.platform.startswith("win"),
+    reason="Symlink behavior on Windows depends on privileges / developer mode",
+)
 def test_do_not_collect_symlink_siblings(
     pytester: Pytester, tmp_path: Path, request: pytest.FixtureRequest
 ) -> None:
-    """
-    Regression test for #12039: Do not collect from directories that are symlinks to other directories in the same path.
+    if not _can_create_symlink(tmp_path):
+        pytest.skip("Symlinks not supported in this environment")
 
-    The check for short paths under Windows via os.path.samefile, introduced in #11936, also finds the symlinked
-    directory created by tmp_path/tmpdir.
-    """
-    # Use tmp_path because it creates a symlink with the name "current" next to the directory it creates.
     symlink_path = tmp_path.parent / (tmp_path.name[:-1] + "current")
     assert symlink_path.is_symlink() is True
 
-    # Create test file.
     tmp_path.joinpath("test_foo.py").write_text("def test(): pass", encoding="UTF-8")
 
-    # Ensure we collect it only once if we pass the tmp_path.
     result = pytester.runpytest(tmp_path, "-sv")
     result.assert_outcomes(passed=1)
 
-    # Ensure we collect it only once if we pass the symlinked directory.
     result = pytester.runpytest(symlink_path, "-sv")
     result.assert_outcomes(passed=1)