long path fixes

Author: Tor Colvin

AUTHORS

@@ -265,6 +265,7 @@ Tom Dalton
 Tom Viner
 Tomáš Gavenčiak
 Tomer Keren
+Tor Colvin
 Trevor Bekolay
 Tyler Goodlet
 Tzu-ping Chung

changelog/6755.bugfix.rst

@@ -0,0 +1 @@
+Support deleting paths longer than 260 characters on windows created inside tmpdir. 

src/_pytest/pathlib.py

@@ -99,11 +99,23 @@ def chmod_rw(p: str) -> None:
     func(path)
     return True
 
+def create_long_path(path: Path) -> Path:
+    """Construct a path which will work on Windows if greater
+    than 260 characters. Resolves into a absolute path which
+    bypasses the typical MAX_PATH limitation:
+    https://docs.microsoft.com/en-us/windows/win32/fileio/naming-a-file#maximum-path-length-limitation"""
+    if sys.platform.startswith("win32"):
+        path = path.resolve()
+        # for the API
+        if not str(path).startswith(r"\\?\"):
+            path = Path(r"\\?\" + str(path))
+    return path
 
 def rm_rf(path: Path) -> None:
     """Remove the path contents recursively, even if some elements
     are read-only.
     """
+    path = create_long_path(path)
     onerror = partial(on_rm_rf_error, start_path=path)
     shutil.rmtree(str(path), onerror=onerror)
 

testing/test_pathlib.py

@@ -89,3 +89,15 @@ def renamed_failed(*args):
     lock_path = get_lock_path(path)
     maybe_delete_a_numbered_dir(path)
     assert not lock_path.is_file()
+
+def test_long_path_during_cleanup(tmp_path):
+    """Ensure that deleting long path works (particularly on Windows (#6775))."""
+    path = tmp_path / ("a" * 200)
+    if sys.platform == "win32":
+        dirname = path.resolve()
+        dirname = r"\\?\" + str(path)
+        os.mkdir(dirname)
+
+    lock_path = get_lock_path(path)
+    maybe_delete_a_numbered_dir(path)
+    assert not lock_path.is_file()