cover missing methods

Author: d-v-b

src/zarr/core/dtype/wrapper.py

@@ -136,11 +136,13 @@ def to_native_dtype(self: Self) -> TDType_co:
 
     @classmethod
     @abstractmethod
-    def _from_json_v2(cls: type[Self], data: DTypeJSON) -> Self: ...
+    def _from_json_v2(cls: type[Self], data: DTypeJSON) -> Self:
+        raise NotImplementedError  # pragma: no cover
 
     @classmethod
     @abstractmethod
-    def _from_json_v3(cls: type[Self], data: DTypeJSON) -> Self: ...
+    def _from_json_v3(cls: type[Self], data: DTypeJSON) -> Self:
+        raise NotImplementedError  # pragma: no cover
 
     @classmethod
     def from_json(cls: type[Self], data: DTypeJSON, *, zarr_format: ZarrFormat) -> Self: