weaken codec JSON test, update crc32c test cases

Author: d-v-b

src/zarr/codecs/crc32c_.py

@@ -44,6 +44,8 @@ def check_json_v2(data: object) -> TypeGuard[Crc32cJSON_V2]:
 
 
 def check_json_v3(data: object) -> TypeGuard[Crc32cJSON_V3]:
+    if data == "crc32c":
+        return True
     return (
         isinstance(data, Mapping)
         and set(data.keys()) in ({"name", "configuration"}, {"name"})

tests/test_codecs/conftest.py

@@ -23,16 +23,24 @@ class BaseTestCodec:
     """
 
     test_cls: type[Codec]
-    valid_json_v2: ClassVar[tuple[CodecJSON_V2, ...]]
-    valid_json_v3: ClassVar[tuple[CodecJSON_V3, ...]]
-
-    def test_from_json_roundtrip_v2(self, valid_json_v2: CodecJSON_V2) -> None:
+    valid_json_v2: ClassVar[tuple[CodecJSON_V2 | object, ...]]
+    valid_json_v3: ClassVar[tuple[CodecJSON_V3 | object, ...]]
+
+    def test_from_json_v2(self, valid_json_v2: CodecJSON_V2) -> None:
+        """
+        Test that the codec generated from valid JSON generates a JSON representation that generates
+        the same codec
+        """
         codec = self.test_cls.from_json(valid_json_v2)
-        assert codec.to_json(zarr_format=2) == valid_json_v2
+        assert codec.from_json(codec.to_json(zarr_format=2)) == codec
 
-    def test_from_json_roundtrip_v3(self, valid_json_v3: CodecJSON_V3) -> None:
+    def test_from_json_v3(self, valid_json_v3: CodecJSON_V3) -> None:
+        """
+        Test that the codec generated from valid JSON generates a JSON representation that generates
+        the same codec
+        """
         codec = self.test_cls.from_json(valid_json_v3)
-        assert codec.to_json(zarr_format=3) == valid_json_v3
+        assert codec.from_json(codec.to_json(zarr_format=3)) == codec
 
 
 def pytest_generate_tests(metafunc: Any) -> None:

tests/test_codecs/test_crc32c.py

@@ -34,8 +34,15 @@
 
 class TestCrc32cCodec(BaseTestCodec):
     test_cls = Crc32cCodec
-    valid_json_v2 = ({"id": "crc32c"},)
-    valid_json_v3 = ({"name": "crc32c"},)
+    valid_json_v2 = (
+        {"id": "crc32c"},
+        pytest.param(
+            {"id": "crc32c", "location": "start"},
+            marks=pytest.mark.xfail(reason="start location not supported"),
+        ),
+        {"id": "crc32c", "location": "end"},
+    )
+    valid_json_v3 = ({"name": "crc32c"}, "crc32c")
 
 
 class TestCrc32cCodecJSON: