def test_join_chunks(self, shape, pref_chunks, req_chunks):
        """Don't warn when the requested chunks join or keep the preferred chunks."""
        initial = self.create_dataset(shape, pref_chunks)
        with assert_no_warnings():
            final = xr.open_dataset(
                initial,
                engine=PassThroughBackendEntrypoint,
                chunks=dict(zip(initial[self.var_name].dims, req_chunks, strict=True)),
            )
        self.check_dataset(initial, final, explicit_chunks(req_chunks, shape))
Don't warn when the requested chunks join or keep the preferred chunks.
xarray/tests/test_backends_api.py