fix #4135 - handle symlinks in tmp path cleanup

changelog/4135.bugfix.rst

@@ -0,0 +1 @@
+pathlib based tmpdir cleanup now correctly handles symlinks in the folder.

src/_pytest/pathlib.py

@@ -173,6 +173,8 @@ def delete_a_numbered_dir(path):
 
 def ensure_deletable(path, consider_lock_dead_if_created_before):
     """checks if a lock exists and breaks it if its considered dead"""
+    if path.is_symlink():
+        return False
     lock = get_lock_path(path)
     if not lock.exists():
         return True

testing/test_tmpdir.py

@@ -1,7 +1,10 @@
 from __future__ import absolute_import, division, print_function
 import sys
-import py
+
+import six
+
 import pytest
+from _pytest.pathlib import Path
 
 
 def test_tmpdir_fixture(testdir):
@@ -65,10 +68,6 @@ def test_1():
     assert mytemp.join("hello").check()
 
 
-@pytest.mark.skipif(
-    not hasattr(py.path.local, "mksymlinkto"),
-    reason="symlink not available on this platform",
-)
 def test_tmpdir_always_is_realpath(testdir):
     # the reason why tmpdir should be a realpath is that
     # when you cd to it and do "os.getcwd()" you will anyway
@@ -78,7 +77,7 @@ def test_tmpdir_always_is_realpath(testdir):
     # os.environ["PWD"]
     realtemp = testdir.tmpdir.mkdir("myrealtemp")
     linktemp = testdir.tmpdir.join("symlinktemp")
-    linktemp.mksymlinkto(realtemp)
+    attempt_symlink_to(linktemp, str(realtemp))
     p = testdir.makepyfile(
         """
         def test_1(tmpdir):
@@ -232,7 +231,7 @@ def test_lock_register_cleanup_removal(self, tmp_path):
 
         assert not lock.exists()
 
-    def test_cleanup_keep(self, tmp_path):
+    def _do_cleanup(self, tmp_path):
         self.test_make(tmp_path)
         from _pytest.pathlib import cleanup_numbered_dir
 
@@ -242,6 +241,9 @@ def test_cleanup_keep(self, tmp_path):
             keep=2,
             consider_lock_dead_if_created_before=0,
         )
+
+    def test_cleanup_keep(self, tmp_path):
+        self._do_cleanup(tmp_path)
         a, b = tmp_path.iterdir()
         print(a, b)
 
@@ -275,3 +277,19 @@ def test_rmtree(self, tmp_path):
 
         rmtree(adir, force=True)
         assert not adir.exists()
+
+    def test_cleanup_symlink(self, tmp_path):
+        the_symlink = tmp_path / (self.PREFIX + "current")
+        attempt_symlink_to(the_symlink, tmp_path / (self.PREFIX + "5"))
+        self._do_cleanup(tmp_path)
+
+
+def attempt_symlink_to(path, to_path):
+    """Try to make a symlink from "path" to "to_path", skipping in case this platform
+    does not support it or we don't have sufficient privileges (common on Windows)."""
+    if sys.platform.startswith("win") and six.PY2:
+        pytest.skip("pathlib for some reason cannot make symlinks on Python 2")
+    try:
+        Path(path).symlink_to(Path(to_path))
+    except OSError:
+        pytest.skip("could not create symbolic link")