Enforce unified list field consistency

Discovered via bug: controller_node field present in
project update list but not in detail view

Added tests to assert that "unified" list serializer
produces same fields as the ordinary serializer,
for unified jobs & unified JTs

Added test to check that list serializers do differ
from detail serializer except for allowed differences

Added test to check that list serializers are applied
correctly - only on list views, and that detail views,
likewise, do not use list serializers

Fix the many many bugs discovered by these new
testing mechanisms

awx/main/tests/unit/api/serializers/test_unified_serializers.py

@@ -0,0 +1,69 @@
+# AWX
+from awx.api import serializers
+from awx.main.models import UnifiedJob, UnifiedJobTemplate
+
+# DRF
+from rest_framework.generics import ListAPIView
+
+
+def test_unified_template_field_consistency():
+    '''
+    Example of what is being tested:
+    The endpoints /projects/N/ and /projects/ should have the same fields as
+    that same project when it is serialized by the unified job template serializer
+    in /unified_job_templates/
+    '''
+    for cls in UnifiedJobTemplate.__subclasses__():
+        detail_serializer = getattr(serializers, '{}Serializer'.format(cls.__name__))
+        unified_serializer = serializers.UnifiedJobTemplateSerializer().get_sub_serializer(cls())
+        assert set(detail_serializer().fields.keys()) == set(unified_serializer().fields.keys())
+
+
+def test_unified_job_list_field_consistency():
+    '''
+    Example of what is being tested:
+    The endpoint /project_updates/ should have the same fields as that
+    project update when it is serialized by the unified job template serializer
+    in /unified_jobs/
+    '''
+    for cls in UnifiedJob.__subclasses__():
+        list_serializer = getattr(serializers, '{}ListSerializer'.format(cls.__name__))
+        unified_serializer = serializers.UnifiedJobListSerializer().get_sub_serializer(cls())
+        assert set(list_serializer().fields.keys()) == set(unified_serializer().fields.keys()), (
+            'Mismatch between {} list serializer & unified list serializer'.format(cls)
+        )
+
+
+def test_unified_job_detail_exclusive_fields():
+    '''
+    For each type, assert that the only fields allowed to be exclusive to
+    detail view are the allowed types
+    '''
+    allowed_detail_fields = frozenset(
+        ('result_traceback', 'job_args', 'job_cwd', 'job_env', 'event_processing_finished')
+    )
+    for cls in UnifiedJob.__subclasses__():
+        list_serializer = getattr(serializers, '{}ListSerializer'.format(cls.__name__))
+        detail_serializer = getattr(serializers, '{}Serializer'.format(cls.__name__))
+        list_fields = set(list_serializer().fields.keys())
+        detail_fields = set(detail_serializer().fields.keys()) - allowed_detail_fields
+        assert list_fields == detail_fields, 'List / detail mismatch for serializers of {}'.format(cls)
+
+
+def test_list_views_use_list_serializers(all_views):
+    '''
+    Check that the list serializers are only used for list views,
+    and vice versa
+    '''
+    list_serializers = tuple(
+        getattr(serializers, '{}ListSerializer'.format(cls.__name__)) for
+        cls in (UnifiedJob.__subclasses__() + [UnifiedJob])
+    )
+    for View in all_views:
+        if hasattr(View, 'model') and issubclass(getattr(View, 'model'), UnifiedJob):
+            if issubclass(View, ListAPIView):
+                assert issubclass(View.serializer_class, list_serializers), (
+                    'View {} serializer {} is not a list serializer'.format(View, View.serializer_class)
+                )
+            else:
+                assert not issubclass(View.model, list_serializers)