Add tests of warnings

lib/iris/tests/unit/fileformats/pyke_rules/compiled_krb/fc_rules_cf_fc/test_build_dimension_coordinate.py

@@ -1,4 +1,4 @@
-# (C) British Crown Copyright 2014 - 2015, Met Office
+# (C) British Crown Copyright 2014 - 2018, Met Office
 #
 # This file is part of Iris.
 #
@@ -112,6 +112,60 @@ def test_dim_coord_construction(self):
             self.engine.cube.add_dim_coord.assert_called_with(
                 expected_coord, [0])
 
+    def test_dim_coord_construction_masked_array(self):
+        self._set_cf_coord_var(np.ma.array(
+            np.arange(6),
+            mask=[True, False, False, False, False, False],
+            fill_value=-999,
+        ))
+
+        expected_coord = DimCoord(
+            np.array([-999, 1, 2, 3, 4, 5]),
+            long_name=self.cf_coord_var.long_name,
+            var_name=self.cf_coord_var.cf_name,
+            units=self.cf_coord_var.units,
+            bounds=self.bounds)
+
+        with warnings.catch_warnings(record=True) as w:
+            # Asserts must lie within context manager because of deferred
+            # loading.
+            with self.deferred_load_patch, self.get_cf_bounds_var_patch:
+                build_dimension_coordinate(self.engine, self.cf_coord_var)
+
+                # Test that expected coord is built and added to cube.
+                self.engine.cube.add_dim_coord.assert_called_with(
+                    expected_coord, [0])
+
+            # Assert warning is raised
+            assert len(w) == 1
+            assert 'Gracefully filling' in w[0].message.args[0]
+
+    def test_dim_coord_construction_masked_array_mask_does_nothing(self):
+        self._set_cf_coord_var(np.ma.array(
+            np.arange(6),
+            mask=False,
+        ))
+
+        expected_coord = DimCoord(
+            self.cf_coord_var[:],
+            long_name=self.cf_coord_var.long_name,
+            var_name=self.cf_coord_var.cf_name,
+            units=self.cf_coord_var.units,
+            bounds=self.bounds)
+
+        with warnings.catch_warnings(record=True) as w:
+            # Asserts must lie within context manager because of deferred
+            # loading.
+            with self.deferred_load_patch, self.get_cf_bounds_var_patch:
+                build_dimension_coordinate(self.engine, self.cf_coord_var)
+
+                # Test that expected coord is built and added to cube.
+                self.engine.cube.add_dim_coord.assert_called_with(
+                    expected_coord, [0])
+
+            # Assert no warning is raised
+            assert len(w) == 0
+
     def test_aux_coord_construction(self):
         # Use non monotonically increasing coordinates to force aux coord
         # construction.