Add comments for requires_pint_0_15

Author: Russell Manser

xarray/tests/__init__.py

@@ -78,6 +78,7 @@ def LooseVersion(vstring):
 has_seaborn, requires_seaborn = _importorskip("seaborn")
 has_sparse, requires_sparse = _importorskip("sparse")
 has_cartopy, requires_cartopy = _importorskip("cartopy")
+# Need Pint 0.15 for __dask_tokenize__ tests for Quantity wrapped Dask Arrays
 has_pint_0_15, requires_pint_0_15 = _importorskip("pint", minversion="0.15")
 
 # some special cases

xarray/tests/test_dask.py

@@ -293,6 +293,7 @@ def test_persist(self):
         self.assertLazyAndAllClose(u + 1, v)
         self.assertLazyAndAllClose(u + 1, v2)
 
+    # Need Pint 0.15 for __dask_tokenize__ implementation
     @requires_pint_0_15
     def test_tokenize_duck_dask_array(self):
         import pint
@@ -732,6 +733,7 @@ def test_from_dask_variable(self):
         a = DataArray(self.lazy_array.variable, coords={"x": range(4)}, name="foo")
         self.assertLazyAndIdentical(self.lazy_array, a)
 
+    # Need Pint 0.15 for __dask_tokenize__ implementation
     @requires_pint_0_15
     def test_tokenize_duck_dask_array(self):
         import pint