Do not collect symlinked tests under Windows

The check for short paths under Windows via os.path.samefile, introduced in pytest-dev#11936, also found similar tests in symlinked tests in the GH Actions CI.
This checks additionally that one of the files is not a symlink.

Fixes pytest-dev#12039.

Author: mrbean-bremen

changelog/12039.bugfix.rst

@@ -0,0 +1 @@
+Fixed a regression in 8.0.2 where tests have been collected multiple times in the CI under Windows

src/_pytest/main.py

@@ -6,6 +6,7 @@
 import functools
 import importlib
 import os
+import stat
 from pathlib import Path
 import sys
 from typing import AbstractSet
@@ -443,6 +444,20 @@ def pytest_collection_modifyitems(items: List[nodes.Item], config: Config) -> No
         items[:] = remaining
 
 
+def _is_junction(path: Path) -> bool:
+    if sys.version_info >= (3, 12):
+        return os.path.isjunction(path)
+
+    if hasattr(os.stat_result, 'st_reparse_tag'):
+        try:
+            st = os.lstat(path)
+        except (OSError, ValueError, AttributeError):
+            return False
+        return bool(st.st_reparse_tag == stat.IO_REPARSE_TAG_MOUNT_POINT)
+
+    return False
+
+
 class FSHookProxy:
     def __init__(
         self,
@@ -907,9 +922,16 @@ def collect(self) -> Iterator[Union[nodes.Item, nodes.Collector]]:
                     if isinstance(matchparts[0], Path):
                         is_match = node.path == matchparts[0]
                         if sys.platform == "win32" and not is_match:
-                            # In case the file paths do not match, fallback to samefile() to
+                            # In case the file paths do not match,
                             # account for short-paths on Windows (#11895).
-                            is_match = os.path.samefile(node.path, matchparts[0])
+                            same_file = os.path.samefile(node.path, matchparts[0])
+                            # we don't want to find links, so we at least
+                            # exclude symlinks to regular directories
+                            is_match = (
+                                    same_file and
+                                    os.path.islink(node.path) == os.path.islink(matchparts[0])
+                            )
+
                     # Name part e.g. `TestIt` in `/a/b/test_file.py::TestIt::test_it`.
                     else:
                         # TODO: Remove parametrized workaround once collection structure contains

testing/test_collection.py

@@ -1765,7 +1765,7 @@ def test_foo(): assert True
 
 @pytest.mark.skipif(not sys.platform.startswith("win"), reason="Windows only")
 def test_collect_short_file_windows(pytester: Pytester) -> None:
-    """Reproducer for #11895: short paths not colleced on Windows."""
+    """Reproducer for #11895: short paths not collected on Windows."""
     short_path = tempfile.mkdtemp()
     if "~" not in short_path:  # pragma: no cover
         if running_on_ci():
@@ -1787,3 +1787,12 @@ def test_collect_short_file_windows(pytester: Pytester) -> None:
     test_file.write_text("def test(): pass", encoding="UTF-8")
     result = pytester.runpytest(short_path)
     assert result.parseoutcomes() == {"passed": 1}
+
+
+def test_collect_symlinks(pytester: Pytester, tmpdir) -> None:
+    """Regression test for #12039: Tests collected multiple times under Windows."""
+    test_file = Path(tmpdir) / "symlink_collection_test.py"
+    test_file.write_text("def test(): pass", encoding="UTF-8")
+    result = pytester.runpytest(tmpdir)
+    # this failed in CI only (GitHub actions)
+    assert result.parseoutcomes() == {"passed": 1}