Fixed #27170 -- Added DatabaseWrapper class attributes to ease subclassing.

2 files changed, 28 insertions, 3 deletions

diff --git a/tests/backends/tests.py b/tests/backends/tests.py
index 4851995149..106fd7f856 100644
--- a/tests/backends/tests.py
+++ b/tests/backends/tests.py
@@ -32,6 +32,31 @@ from django.utils.six.moves import range
 from . import models
 
 
+class DatabaseWrapperTests(SimpleTestCase):
+
+    def test_initialization_class_attributes(self):
+        """
+        The "initialization" class attributes like client_class and
+        creation_class should be set on the class and reflected in the
+        corresponding instance attributes of the instantiated backend.
+        """
+        conn = connections[DEFAULT_DB_ALIAS]
+        conn_class = type(conn)
+        attr_names = [
+            ('client_class', 'client'),
+            ('creation_class', 'creation'),
+            ('features_class', 'features'),
+            ('introspection_class', 'introspection'),
+            ('ops_class', 'ops'),
+            ('validation_class', 'validation'),
+        ]
+        for class_attr_name, instance_attr_name in attr_names:
+            class_attr_value = getattr(conn_class, class_attr_name)
+            self.assertIsNotNone(class_attr_value)
+            instance_attr_value = getattr(conn, instance_attr_name)
+            self.assertIsInstance(instance_attr_value, class_attr_value)
+
+
 class DummyBackendTest(SimpleTestCase):
 
     def test_no_databases(self):
diff --git a/tests/test_runner/tests.py b/tests/test_runner/tests.py
index c2ad07013c..15417db645 100644
--- a/tests/test_runner/tests.py
+++ b/tests/test_runner/tests.py
@@ -281,7 +281,7 @@ class SetupDatabasesTests(unittest.TestCase):
             }
         })
 
-        with mock.patch('django.db.backends.dummy.base.DatabaseCreation') as mocked_db_creation:
+        with mock.patch('django.db.backends.dummy.base.DatabaseWrapper.creation_class') as mocked_db_creation:
             with mock.patch('django.test.utils.connections', new=tested_connections):
                 old_config = self.runner_instance.setup_databases()
                 self.runner_instance.teardown_databases(old_config)
@@ -306,7 +306,7 @@ class SetupDatabasesTests(unittest.TestCase):
                 'ENGINE': 'django.db.backends.dummy',
             },
         })
-        with mock.patch('django.db.backends.dummy.base.DatabaseCreation') as mocked_db_creation:
+        with mock.patch('django.db.backends.dummy.base.DatabaseWrapper.creation_class') as mocked_db_creation:
             with mock.patch('django.test.utils.connections', new=tested_connections):
                 self.runner_instance.setup_databases()
         mocked_db_creation.return_value.create_test_db.assert_called_once_with(
@@ -320,7 +320,7 @@ class SetupDatabasesTests(unittest.TestCase):
                 'TEST': {'SERIALIZE': False},
             },
         })
-        with mock.patch('django.db.backends.dummy.base.DatabaseCreation') as mocked_db_creation:
+        with mock.patch('django.db.backends.dummy.base.DatabaseWrapper.creation_class') as mocked_db_creation:
             with mock.patch('django.test.utils.connections', new=tested_connections):
                 self.runner_instance.setup_databases()
         mocked_db_creation.return_value.create_test_db.assert_called_once_with(