Fix 500 error due to None data in DAB response (ansible#15562)

* Fix 500 error due to None data in DAB response

* NOQA for flake8 failures

awx/api/generics.py

@@ -244,7 +244,8 @@ def finalize_response(self, request, response, *args, **kwargs):
             if hasattr(self, '__init_request_error__'):
                 response = self.handle_exception(self.__init_request_error__)
             if response.status_code == 401:
-                response.data['detail'] += _(' To establish a login session, visit') + ' /api/login/.'
+                if response.data and 'detail' in response.data:
+                    response.data['detail'] += _(' To establish a login session, visit') + ' /api/login/.'
                 logger.info(status_msg)
             else:
                 logger.warning(status_msg)

awx/main/tests/functional/api/test_user.py

@@ -4,6 +4,11 @@
 import pytest
 
 from django.contrib.sessions.middleware import SessionMiddleware
+from django.test.utils import override_settings
+from django.contrib.auth.models import AnonymousUser
+
+from ansible_base.lib.utils.response import get_relative_url
+from ansible_base.lib.testing.fixtures import settings_override_mutable  # NOQA: F401 imported to be a pytest fixture
 
 from awx.main.models import User
 from awx.api.versioning import reverse
@@ -16,6 +21,33 @@
 EXAMPLE_USER_DATA = {"username": "affable", "first_name": "a", "last_name": "a", "email": "a@a.com", "is_superuser": False, "password": "r$TyKiOCb#ED"}
 
 
+@pytest.mark.django_db
+def test_validate_local_user(post, admin_user, settings, settings_override_mutable):  # NOQA: F811 this is how you use a pytest fixture
+    "Copy of the test by same name in django-ansible-base for integration and compatibility testing"
+    url = get_relative_url('validate-local-account')
+    admin_user.set_password('password')
+    admin_user.save()
+    data = {
+        "username": admin_user.username,
+        "password": "password",
+    }
+    with override_settings(RESOURCE_SERVER={"URL": "https://foo.invalid", "SECRET_KEY": "foobar"}):
+        response = post(url=url, data=data, user=AnonymousUser(), expect=200)
+
+    assert 'ansible_id' in response.data
+    assert response.data['auth_code'] is not None, response.data
+
+    # No resource server, return coherent response but can not provide auth code
+    response = post(url=url, data=data, user=AnonymousUser(), expect=200)
+    assert 'ansible_id' in response.data
+    assert response.data['auth_code'] is None
+
+    # wrong password
+    data['password'] = 'foobar'
+    response = post(url=url, data=data, user=AnonymousUser(), expect=401)
+    # response.data may be none here, this is just testing that we get no server error
+
+
 @pytest.mark.django_db
 def test_user_create(post, admin):
     response = post(reverse('api:user_list'), EXAMPLE_USER_DATA, admin, middleware=SessionMiddleware(mock.Mock()))