test_gce: Fix invalid mock of platform_reports_gce to return False

The mock of platform_reports_gce is created with a True return value in
tests/unittests/test_datasource/test_gce.py:TestDataSourceGCE.setUp().
But, the final test_get_data_returns_false_if_not_on_gce incorrectly
attempts to override the mocked return_value of True to False by setting
self.m_platform_gce.return_value = False. But, since the mock is already
initialized, the updated False is not honored. Instead we should use the
patch decorator on the specific unit test to override the return_value of
DataSourceGCE.platform_reports_gce to False.

A False from platform_reports_gce allows DataSourceGCE.get_data to
immediately return False instead of trying to contact
metadata.google.internal as the related bug references.

1 files changed, 3 insertions, 2 deletions

diff --git a/tests/unittests/test_datasource/test_gce.py b/tests/unittests/test_datasource/test_gce.py
index 6fd1341d..3e8398b3 100644
--- a/tests/unittests/test_datasource/test_gce.py
+++ b/tests/unittests/test_datasource/test_gce.py
@@ -163,8 +163,9 @@ class TestDataSourceGCE(test_helpers.HttprettyTestCase):
         self.assertEqual(True, r)
         self.assertEqual('bar', self.ds.availability_zone)
 
-    def test_get_data_returns_false_if_not_on_gce(self):
-        self.m_platform_reports_gce.return_value = False
+    @mock.patch('cloudinit.sources.DataSourceGCE.platform_reports_gce')
+    def test_get_data_returns_false_if_not_on_gce(self, m_platform_gce):
+        m_platform_gce.return_value = False
         self.assertEqual(False, self.ds.get_data())