Move _uniquepath to pathlib as unique_path.

Co-authored-by: Bruno Oliveira <nicoddemus@gmail.com>

src/_pytest/config/__init__.py

@@ -30,16 +30,13 @@ from _pytest._code import filter_traceback
 from _pytest.compat import importlib_metadata
 from _pytest.outcomes import fail
 from _pytest.outcomes import Skipped
+from _pytest.pathlib import unique_path
 from _pytest.warning_types import PytestConfigWarning
 
 hookimpl = HookimplMarker("pytest")
 hookspec = HookspecMarker("pytest")
 
 
-def _uniquepath(path):
-    return type(path)(os.path.normcase(str(path.realpath())))
-
-
 class ConftestImportFailure(Exception):
     def __init__(self, path, excinfo):
         Exception.__init__(self, path, excinfo)
@@ -370,7 +367,7 @@ class PytestPluginManager(PluginManager):
         """
         current = py.path.local()
         self._confcutdir = (
-            _uniquepath(current.join(namespace.confcutdir, abs=True))
+            unique_path(current.join(namespace.confcutdir, abs=True))
             if namespace.confcutdir
             else None
         )
@@ -409,7 +406,7 @@ class PytestPluginManager(PluginManager):
         else:
             directory = path
 
-        directory = _uniquepath(directory)
+        directory = unique_path(directory)
 
         # XXX these days we may rather want to use config.rootdir
         # and allow users to opt into looking into the rootdir parent
@@ -438,7 +435,7 @@ class PytestPluginManager(PluginManager):
         # Use realpath to avoid loading the same conftest twice
         # with build systems that create build directories containing
         # symlinks to actual files.
-        conftestpath = _uniquepath(conftestpath)
+        conftestpath = unique_path(conftestpath)
         try:
             return self._conftestpath2mod[conftestpath]
         except KeyError:

src/_pytest/pathlib.py

@@ -11,6 +11,7 @@ from functools import partial
 from os.path import expanduser
 from os.path import expandvars
 from os.path import isabs
+from os.path import normcase
 from os.path import sep
 from posixpath import sep as posix_sep
 
@@ -334,3 +335,12 @@ def fnmatch_ex(pattern, path):
 def parts(s):
     parts = s.split(sep)
     return {sep.join(parts[: i + 1]) or sep for i in range(len(parts))}
+
+
+def unique_path(path):
+    """Returns a unique path in case-insensitive (but case-preserving) file
+    systems such as Windows.
+
+    This is needed only for ``py.path.local``; ``pathlib.Path`` handles this
+    natively with ``resolve()``."""
+    return type(path)(normcase(str(path.realpath())))