Change case handling for pathlib

- make it depend on posic vs. windows instead of case sensitivity of
file system
- see pytest-dev#167

fake_pathlib_test.py

@@ -485,6 +485,24 @@ def test_glob(self):
         self.assertEqual(sorted(path.glob('*.py')),
                          [self.path('!foo!all_tests.py'), self.path('!foo!setup.py')])
 
+    def test_glob_case_windows(self):
+        self.filesystem.is_windows_fs = True
+        self.filesystem.CreateFile('!foo!setup.py')
+        self.filesystem.CreateFile('!foo!all_tests.PY')
+        self.filesystem.CreateFile('!foo!README.md')
+        self.filesystem.CreateFile('!foo!example.Py')
+        path = self.path('!foo')
+        self.assertEqual(sorted(path.glob('*.py')),
+                         [self.path('!foo!all_tests.PY'), self.path('!foo!example.Py'), self.path('!foo!setup.py')])
+
+    def test_glob_case_posix(self):
+        self.filesystem.is_windows_fs = False
+        self.filesystem.CreateFile('!foo!setup.py')
+        self.filesystem.CreateFile('!foo!all_tests.PY')
+        self.filesystem.CreateFile('!foo!README.md')
+        self.filesystem.CreateFile('!foo!example.Py')
+        path = self.path('!foo')
+        self.assertEqual(sorted(path.glob('*.py')), [self.path('!foo!setup.py')])
 
 @unittest.skipIf(sys.version_info < (3, 6), 'path-like objects new in Python 3.6')
 class FakePathlibUsageInOsFunctionsTest(unittest.TestCase):

pyfakefs/fake_pathlib.py

@@ -208,15 +208,15 @@ def splitroot(self, path, sep=None):
 
     def casefold(self, s):
         """Return the lower-case version of s for a case-insensitive filesystem."""
-        if self.filesystem.is_case_sensitive:
-            return s
-        return s.lower()
+        if self.filesystem.is_windows_fs:
+            return s.lower()
+        return s
 
     def casefold_parts(self, parts):
         """Return the lower-case version of parts for a case-insensitive filesystem."""
-        if self.filesystem.is_case_sensitive:
-            return parts
-        return [p.lower() for p in parts]
+        if self.filesystem.is_windows_fs:
+            return [p.lower() for p in parts]
+        return parts
 
     def _resolve_posix(self, path, strict):
         """Original implementation in Python 3.6."""