Fix metadata defaults

* Metadata defaults were not being set if only a few fields were missing.

* ansible-doc with no documentation and no status in metadata should
  return empty, just like if there was no documentation and no metadata
  at all.

changelogs/fragments/fix-metadata-defaults.yml

@@ -0,0 +1,5 @@
+bugfixes:
+- Plugin Metadata is supposed to have default values.  When the metadata was
+  missing entirely, we were properly setting the defaults.  Fixed the metadata
+  parsing so that the defaults are also set when we were missing just a few
+  fields.

lib/ansible/parsing/plugin_docs.py

@@ -67,9 +67,16 @@ def read_docstring(filename, verbose=True, ignore_errors=True):
 
         if data['metadata']:
             # remove version
-            for x in ('version', 'metadata_version'):
-                if x in data['metadata']:
-                    del data['metadata'][x]
+            for field in ('version', 'metadata_version'):
+                if field in data['metadata']:
+                    del data['metadata'][field]
+
+            if 'supported_by' not in data['metadata']:
+                data['metadata']['supported_by'] = 'community'
+
+            if 'status' not in data['metadata']:
+                data['metadata']['status'] = ['preview']
+
         else:
             # Add default metadata
             data['metadata'] = {'supported_by': 'community',

test/integration/targets/ansible-doc/test.yml

@@ -85,8 +85,8 @@
       register: result
     - assert:
         that:
-          - 'result is failed'
-          - '"ERROR! module test_no_docs_no_status missing documentation (or could not parse documentation): test_no_docs_no_status did not contain a DOCUMENTATION attribute" in result.stderr'
+          - 'result.stdout == ""'
+          - 'result.stderr == ""'
 
     - name: module with no documentation and non-iterable status in metadata
       command: ansible-doc test_no_docs_non_iterable_status