Review changes.

lib/iris/tests/unit/fileformats/rules/test__make_cube.py

@@ -23,6 +23,7 @@
 # importing anything else.
 import iris.tests as tests
 
+import six
 import warnings
 
 from iris.fileformats.rules import ConversionMetadata
@@ -51,7 +52,10 @@ def test_invalid_units(self):
                                       dim_coords_and_dims, aux_coords_and_dims)
         converter = mock.Mock(return_value=metadata)
 
-        field = mock.Mock(core_data=lambda: np.arange(3.), bmdi=9999.)
+        data = np.arange(3.)
+        field = mock.Mock(core_data=lambda: data,
+                          bmdi=9999.,
+                          realised_dtype=data.dtype)
         with warnings.catch_warnings(record=True) as warn:
             warnings.simplefilter("always")
             cube, factories, references = _make_cube(field, converter)
@@ -64,7 +68,7 @@ def test_invalid_units(self):
         # Check warning was raised.
         self.assertEqual(len(warn), 1)
         exp_emsg = 'invalid units {!r}'.format(units)
-        self.assertRegexpMatches(str(warn[0]), exp_emsg)
+        six.assertRegex(self, str(warn[0]), exp_emsg)
 
 
 if __name__ == "__main__":