Do not log warning on config files that represent None.

This issue was first identified when manual_cache_clean was set, as
ds-identify would write /run/cloud-init/cloud.cfg with
  # manual_cache_clean
that would generate a warning as cloud-init expected to load a dict.
Any other "empty" config would also log such a warning.

Also fix reading of di_report to allow it to be None, as ds-identify
would write:
  di_report:
    # manual_cache_clean
which reads as 'di_report: None' rather than di_report: {}.

LP: #1742479

1 files changed, 8 insertions, 0 deletions

diff --git a/tests/unittests/test_util.py b/tests/unittests/test_util.py
index 787ca208..d63b760e 100644
--- a/tests/unittests/test_util.py
+++ b/tests/unittests/test_util.py
@@ -299,6 +299,14 @@ class TestLoadYaml(helpers.TestCase):
                                         default=self.mydefault),
                          myobj)
 
+    def test_none_returns_default(self):
+        """If yaml.load returns None, then default should be returned."""
+        blobs = ("", " ", "# foo\n", "#")
+        mdef = self.mydefault
+        self.assertEqual(
+            [(b, self.mydefault) for b in blobs],
+            [(b, util.load_yaml(blob=b, default=mdef)) for b in blobs])
+
 
 class TestMountinfoParsing(helpers.ResourceUsingTestCase):
     def test_invalid_mountinfo(self):