Fix broken doctest and tests on accessors

cupy_xarray/accessors.py

@@ -5,10 +5,13 @@
     register_dataarray_accessor,
     register_dataset_accessor,
 )
-from xarray.namedarray.pycompat import DuckArrayModule
 
-dsk = DuckArrayModule("dask")
-dask_array_type = dsk.type
+try:
+    import dask.array
+
+    dask_array_type = dask.array.Array
+except ImportError:
+    dask_array_type = None
 
 
 @register_dataarray_accessor("cupy")
@@ -55,7 +58,7 @@ def as_cupy(self):
         >>> da = xr.tutorial.load_dataset("air_temperature").air
         >>> gda = da.cupy.as_cupy()
         >>> type(gda.data)
-        <class 'cupy.core.core.ndarray'>
+        <class 'cupy.ndarray'>
 
         """
         if isinstance(self.da.data, dask_array_type):

cupy_xarray/tests/test_accessors.py

@@ -1,10 +1,16 @@
 import numpy as np
 import pytest
 import xarray as xr
-from xarray.core.pycompat import dask_array_type
 
 import cupy_xarray  # noqa: F401
 
+try:
+    import dask.array
+
+    dask_array_type = dask.array.Array
+except ImportError:
+    dask_array_type = None
+
 
 @pytest.fixture
 def tutorial_ds_air():

docs/source/contributing.rst

@@ -132,7 +132,7 @@ Running the test suite
 *cupy-xarray* uses the `pytest <https://docs.pytest.org/en/latest/contents.html>`_
 framework for testing. You can run the test suite using::
 
-    pytest cupy-xarray
+    pytest --doctest-modules cupy_xarray
 
 Contributing documentation
 ==========================