Combine datetime64 and timedelta64 zarr tests; add cftime zarr test

Author: spencerkclark

xarray/tests/test_backends.py

@@ -48,6 +48,7 @@
 )
 from xarray.backends.pydap_ import PydapDataStore
 from xarray.backends.scipy_ import ScipyBackendEntrypoint
+from xarray.coding.cftime_offsets import cftime_range
 from xarray.coding.strings import check_vlen_dtype, create_vlen_dtype
 from xarray.coding.variables import SerializationWarning
 from xarray.conventions import encode_dataset_coordinates
@@ -2810,18 +2811,22 @@ def test_attributes(self, obj) -> None:
                 ds.to_zarr(store_target, **self.version_kwargs)
 
     @requires_dask
-    def test_chunked_datetime64(self) -> None:
-        # Copied from @malmans2's PR #8253
-        original = create_test_data().astype("datetime64[ns]").chunk(1)
+    @pytest.mark.parametrize("dtype", ["datetime64[ns]", "timedelta64[ns]"])
+    def test_chunked_datetime64_or_timedelta64(self, dtype) -> None:
+        # Generalized from test in @malmans2's PR #8253
+        original = create_test_data().astype(dtype).chunk(1)
         with self.roundtrip(original, open_kwargs={"chunks": {}}) as actual:
             for name, actual_var in actual.variables.items():
                 assert original[name].chunks == actual_var.chunks
             assert original.chunks == actual.chunks
 
+    @requires_cftime
     @requires_dask
-    def test_chunked_timedelta64(self) -> None:
-        # Based @malmans2's datetime64[ns] test in PR #8253
-        original = create_test_data().astype("timedelta64[ns]").chunk(1)
+    def test_chunked_cftime_datetime(self) -> None:
+        # Based on @malmans2's test in PR #8253
+        times = cftime_range("2000", freq="D", periods=3)
+        original = xr.Dataset(data_vars={"chunked_times": (["time"], times)})
+        original = original.chunk({"time": 1})
         with self.roundtrip(original, open_kwargs={"chunks": {}}) as actual:
             for name, actual_var in actual.variables.items():
                 assert original[name].chunks == actual_var.chunks