use assert_called_once_with because assert_called_once will always pass because that method does not exist on mock.MagicMock

celery/tests/backends/test_mongodb.py

@@ -10,7 +10,7 @@ from celery.backends import mongodb as module
 from celery.backends.mongodb import MongoBackend, Bunch, pymongo
 from celery.exceptions import ImproperlyConfigured
 from celery.tests.case import (
-    AppCase, MagicMock, Mock, SkipTest,
+    AppCase, MagicMock, Mock, SkipTest, ANY,
     depends_on_current_app, patch, sentinel,
 )
 
@@ -176,7 +176,7 @@ class test_MongoBackend(AppCase):
 
         mock_get_database.assert_called_once_with()
         mock_database.__getitem__.assert_called_once_with(MONGODB_COLLECTION)
-        mock_collection.save.assert_called_once()
+        mock_collection.save.assert_called_once_with(ANY)
         self.assertEqual(sentinel.result, ret_val)
 
     @patch('celery.backends.mongodb.MongoBackend._get_database')
@@ -232,7 +232,7 @@ class test_MongoBackend(AppCase):
 
         mock_get_database.assert_called_once_with()
         mock_database.__getitem__.assert_called_once_with(MONGODB_COLLECTION)
-        mock_collection.save.assert_called_once()
+        mock_collection.save.assert_called_once_with(ANY)
         self.assertEqual(sentinel.result, ret_val)
 
     @patch('celery.backends.mongodb.MongoBackend._get_database')
@@ -309,7 +309,7 @@ class test_MongoBackend(AppCase):
         mock_get_database.assert_called_once_with()
         mock_database.__getitem__.assert_called_once_with(
             MONGODB_COLLECTION)
-        mock_collection.assert_called_once()
+        mock_collection.assert_called_once_with()
 
     def test_get_database_authfailure(self):
         x = MongoBackend(app=self.app)

celery/tests/case.py

@@ -45,7 +45,7 @@ from celery.utils.functional import noop
 from celery.utils.imports import qualname
 
 __all__ = [
-    'Case', 'AppCase', 'Mock', 'MagicMock',
+    'Case', 'AppCase', 'Mock', 'MagicMock', 'ANY',
     'patch', 'call', 'sentinel', 'skip_unless_module',
     'wrap_logger', 'with_environ', 'sleepdeprived',
     'skip_if_environ', 'todo', 'skip', 'skip_if',
@@ -59,6 +59,7 @@ patch = mock.patch
 call = mock.call
 sentinel = mock.sentinel
 MagicMock = mock.MagicMock
+ANY = mock.ANY
 
 CASE_REDEFINES_SETUP = """\
 {name} (subclass of AppCase) redefines private "setUp", should be: "setup"\