bring in purepath and fix an assertion

src/pytest.py

@@ -26,6 +26,7 @@ from _pytest.warning_types import (
     RemovedInPytest4Warning,
     PytestExperimentalApiWarning,
 )
+from _pytest.compat import Path, PurePath
 
 set_trace = __pytestPDB.set_trace
 
@@ -67,6 +68,8 @@ __all__ = [
     "warns",
     "xfail",
     "yield_fixture",
+    "Path",
+    "PurePath",
 ]
 
 if __name__ == "__main__":

testing/test_tmpdir.py

@@ -111,7 +111,7 @@ def test_tmpdir_factory(testdir):
         def session_dir(tmpdir_factory):
             return tmpdir_factory.mktemp('data', numbered=False)
         def test_some(session_dir):
-            session_dir.isdir()
+            assert session_dir.isdir()
     """
     )
     reprec = testdir.inline_run()