Use mock in tests

Author: DPeterK

lib/iris/fileformats/netcdf.py

@@ -2245,7 +2245,9 @@ def is_valid_packspec(p):
                        least_significant_digit, packing=packspec)
 
         if iris.config.netcdf.conventions_override:
-            conventions = cube.attributes['Conventions']
+            # Set to the default if custom conventions are not available.
+            conventions = cube.attributes.get('Conventions',
+                                              CF_CONVENTIONS_VERSION)
         else:
             conventions = CF_CONVENTIONS_VERSION
 

lib/iris/tests/unit/config/test_NetCDF.py

@@ -14,7 +14,7 @@
 #
 # You should have received a copy of the GNU Lesser General Public License
 # along with Iris.  If not, see <http://www.gnu.org/licenses/>.
-"""Unit tests for the `iris.options.Paralle` class."""
+"""Unit tests for the `iris.config.NetCDF` class."""
 
 from __future__ import (absolute_import, division, print_function)
 from six.moves import (filter, input, map, range, zip)  # noqa
@@ -30,27 +30,30 @@
 
 
 class Test(tests.IrisTest):
+    def setUp(self):
+        self.options = iris.config.NetCDF()
+
     def test_basic(self):
-        self.assertFalse(iris.config.netcdf.conventions_override)
+        self.assertFalse(self.options.conventions_override)
 
     def test_enabled(self):
-        iris.config.netcdf.conventions_override = True
-        self.assertTrue(iris.config.netcdf.conventions_override)
+        self.options.conventions_override = True
+        self.assertTrue(self.options.conventions_override)
 
     def test_bad_value(self):
         # A bad value should be ignored and replaced with the default value.
         bad_value = 'wibble'
         with warnings.catch_warnings(record=True) as w:
             warnings.simplefilter('always')
-            iris.config.netcdf.conventions_override = bad_value
-        self.assertFalse(iris.config.netcdf.conventions_override)
+            self.options.conventions_override = bad_value
+        self.assertFalse(self.options.conventions_override)
         exp_wmsg = 'Attempting to set invalid value {!r}'.format(bad_value)
         six.assertRegex(self, str(w[0].message), exp_wmsg)
 
     def test__contextmgr(self):
-        with iris.config.netcdf.context(conventions_override=True):
-            self.assertTrue(iris.config.netcdf.conventions_override)
-        self.assertFalse(iris.config.netcdf.conventions_override)
+        with self.options.context(conventions_override=True):
+            self.assertTrue(self.options.conventions_override)
+        self.assertFalse(self.options.conventions_override)
 
 
 if __name__ == '__main__':

lib/iris/tests/unit/fileformats/netcdf/test_save.py

@@ -23,6 +23,7 @@
 # importing anything else.
 import iris.tests as tests
 
+import mock
 import netCDF4 as nc
 import numpy as np
 
@@ -37,6 +38,7 @@ def setUp(self):
         self.cube = Cube([0])
         self.custom_conventions = 'convention1 convention2'
         self.cube.attributes['Conventions'] = self.custom_conventions
+        self.options = iris.config.netcdf
 
     def test_custom_conventions__ignored(self):
         # Ensure that we drop existing conventions attributes and replace with
@@ -51,14 +53,26 @@ def test_custom_conventions__ignored(self):
     def test_custom_conventions__allowed(self):
         # Ensure that existing conventions attributes are passed through if the
         # relevant Iris option is set.
-        with iris.config.netcdf.context(conventions_override=True):
+        with mock.patch.object(self.options, 'conventions_override', True):
             with self.temp_filename('.nc') as nc_path:
                 save(self.cube, nc_path, 'NETCDF4')
                 ds = nc.Dataset(nc_path)
                 res = ds.getncattr('Conventions')
                 ds.close()
         self.assertEqual(res, self.custom_conventions)
 
+    def test_custom_conventions__allowed__missing(self):
+        # Ensure the default conventions attribute is set if the relevant Iris
+        # option is set but there is no custom conventions attribute.
+        del self.cube.attributes['Conventions']
+        with mock.patch.object(self.options, 'conventions_override', True):
+            with self.temp_filename('.nc') as nc_path:
+                save(self.cube, nc_path, 'NETCDF4')
+                ds = nc.Dataset(nc_path)
+                res = ds.getncattr('Conventions')
+                ds.close()
+        self.assertEqual(res, CF_CONVENTIONS_VERSION)
+
 
 class Test_attributes(tests.IrisTest):
     def test_attributes_arrays(self):