created django_use_model marker for testing unmanaged models;

cherry-picked from d466743

Author: Jakub Owczarski

pytest_django/plugin.py

@@ -418,15 +418,15 @@ def _django_use_model(request):
     else:
         models = (model,)
 
-    with connection.schema_editor() as schema:
+    with contextlib.closing(connection.schema_editor()) as schema:
         schema.deferred_sql = []
         for model_class in models:
             if not hasattr(model, '_meta'):
                 raise ValueError('"model" must be a valid model class')
             schema.create_model(model_class)
 
     def drop():
-        with connection.schema_editor() as schema:
+        with contextlib.closing(connection.schema_editor()) as schema:
             for model_class in models:
                 schema.delete_model(model_class)
 

tests/test_database.py

@@ -141,8 +141,6 @@ def test_transactions_enabled(self):
         assert not connection.in_atomic_block
 
 
-@pytest.mark.skipif(not hasattr(connection, 'schema_editor'),
-                    reason="This Django version does not support SchemaEditor")
 @pytest.mark.django_db
 class TestUseModel:
     """Tests for django_use_model marker"""