Fix MemoryPath root (#495)

* tests: add test case ensuring all parents are absolute

* upath.implementations.memory: fix memorypath root

* tests: skip parents mock test on windows

Author: ap--

upath/implementations/memory.py

@@ -44,7 +44,12 @@ def iterdir(self) -> Iterator[Self]:
     @property
     def path(self) -> str:
         path = super().path
-        return "/" if path == "." else path
+        return "/" if path in {"", "."} else path
+
+    def is_absolute(self) -> bool:
+        if self._relative_base is None and self.__vfspath__() == "/":
+            return True
+        return super().is_absolute()
 
     def __str__(self) -> str:
         s = super().__str__()

upath/tests/cases.py

@@ -782,3 +782,9 @@ def test_trailing_slash_is_stripped(self):
         else:
             assert not self.path.joinpath("key").path.endswith("/")
             assert not self.path.joinpath("key/").path.endswith("/")
+
+    def test_parents_are_absolute(self):
+        # this is a cross implementation compatible way to ensure that
+        # the path representing the root is absolute
+        is_absolute = [p.is_absolute() for p in self.path.parents]
+        assert all(is_absolute)

upath/tests/implementations/test_data.py

@@ -300,3 +300,7 @@ def test_trailing_slash_joinpath_is_identical(self):
     @pytest.mark.skip(reason="DataPath does not support joins")
     def test_trailing_slash_is_stripped(self):
         pass
+
+    @pytest.mark.skip(reason="DataPath does not support joins")
+    def test_parents_are_absolute(self):
+        pass

upath/tests/test_core.py

@@ -79,6 +79,13 @@ def test_iterdir_no_dir(self):
         # so this test would need to have an iterdir fix.
         super().test_iterdir_no_dir()
 
+    @pytest.mark.skipif(
+        sys.platform.startswith("win"),
+        reason="mock fs is not well defined on windows",
+    )
+    def test_parents_are_absolute(self):
+        return super().test_parents_are_absolute()
+
 
 def test_multiple_backend_paths(local_testdir):
     path = "s3://bucket/"