Handle windows volume paths

When a relative path is expanded and we're on a windows platform,
it expands to include the drive, eg C:\ , which was causing a ConfigError
as we split on ":" in parse_volume_spec and that was giving too many parts.

Use os.path.splitdrive instead of manually calculating the drive.

This should help us deal with windows drives as part of the volume
path better than us doing it manually.

Signed-off-by: Mazz Mosley <mazz@houseofmnowster.com>

tests/unit/config/config_test.py

@@ -1124,6 +1124,21 @@ class ExpandPathTest(unittest.TestCase):
         self.assertEqual(result, user_path + 'otherdir/somefile')
 
 
+class VolumePathTest(unittest.TestCase):
+
+    @pytest.mark.xfail((not IS_WINDOWS_PLATFORM), reason='does not have a drive')
+    def test_split_path_mapping_with_windows_path(self):
+        windows_volume_path = "c:\\Users\\msamblanet\\Documents\\anvil\\connect\\config:/opt/connect/config:ro"
+        expected_mapping = (
+            "/opt/connect/config:ro",
+            "c:\\Users\\msamblanet\\Documents\\anvil\\connect\\config"
+        )
+
+        mapping = config.split_path_mapping(windows_volume_path)
+
+        self.assertEqual(mapping, expected_mapping)
+
+
 @pytest.mark.xfail(IS_WINDOWS_PLATFORM, reason='paths use slash')
 class BuildPathTest(unittest.TestCase):
     def setUp(self):

tests/unit/service_test.py

@@ -466,6 +466,21 @@ class ServiceVolumesTest(unittest.TestCase):
         with self.assertRaises(ConfigError):
             parse_volume_spec('one:two:three:four')
 
+    @pytest.mark.xfail((not IS_WINDOWS_PLATFORM), reason='does not have a drive')
+    def test_parse_volume_windows_relative_path(self):
+        windows_relative_path = "c:\\Users\\msamblanet\\Documents\\anvil\\connect\\config:\\opt\\connect\\config:ro"
+
+        spec = parse_volume_spec(windows_relative_path)
+
+        self.assertEqual(
+            spec,
+            (
+                "c:\\Users\\msamblanet\\Documents\\anvil\\connect\\config",
+                "\\opt\\connect\\config",
+                "ro"
+            )
+        )
+
     def test_build_volume_binding(self):
         binding = build_volume_binding(parse_volume_spec('/outside:/inside'))
         self.assertEqual(binding, ('/inside', '/outside:/inside:rw'))