fix some complexity issues

tests/test_same_table_joins.py

@@ -69,7 +69,7 @@ def create_test_database():
 
 @pytest.fixture()
 async def init_relation():
-    department = await Department.objects.create(id=1, name='Math Department')
+    department = await Department.objects.create(id=1, name="Math Department")
     class1 = await SchoolClass.objects.create(name="Math", department=department)
     category = await Category.objects.create(name="Foreign")
     category2 = await Category.objects.create(name="Domestic")
@@ -85,35 +85,41 @@ async def init_relation():
 @pytest.mark.asyncio
 async def test_model_multiple_instances_of_same_table_in_schema(init_relation):
     async with database:
-        classes = await SchoolClass.objects.select_related(['teachers__category', 'students']).all()
-        assert classes[0].name == 'Math'
-        assert classes[0].students[0].name == 'Jane'
+        classes = await SchoolClass.objects.select_related(
+            ["teachers__category", "students"]
+        ).all()
+        assert classes[0].name == "Math"
+        assert classes[0].students[0].name == "Jane"
 
         # related fields of main model are only populated by pk
         # unless there is a required foreign key somewhere along the way
         # since department is required for schoolclass it was pre loaded (again)
         # but you can load them anytime
-        assert classes[0].students[0].schoolclass.name == 'Math'
+        assert classes[0].students[0].schoolclass.name == "Math"
         assert classes[0].students[0].schoolclass.department.name is None
         await classes[0].students[0].schoolclass.department.load()
-        assert classes[0].students[0].schoolclass.department.name == 'Math Department'
+        assert classes[0].students[0].schoolclass.department.name == "Math Department"
 
 
 @pytest.mark.asyncio
 async def test_right_tables_join(init_relation):
     async with database:
-        classes = await SchoolClass.objects.select_related(['teachers__category', 'students']).all()
-        assert classes[0].teachers[0].category.name == 'Domestic'
+        classes = await SchoolClass.objects.select_related(
+            ["teachers__category", "students"]
+        ).all()
+        assert classes[0].teachers[0].category.name == "Domestic"
 
         assert classes[0].students[0].category.name is None
         await classes[0].students[0].category.load()
-        assert classes[0].students[0].category.name == 'Foreign'
+        assert classes[0].students[0].category.name == "Foreign"
 
 
 @pytest.mark.asyncio
 async def test_multiple_reverse_related_objects(init_relation):
     async with database:
-        classes = await SchoolClass.objects.select_related(['teachers__category', 'students']).all()
-        assert classes[0].name == 'Math'
-        assert classes[0].students[1].name == 'Jack'
-        assert classes[0].teachers[0].category.name == 'Domestic'
+        classes = await SchoolClass.objects.select_related(
+            ["teachers__category", "students"]
+        ).all()
+        assert classes[0].name == "Math"
+        assert classes[0].students[1].name == "Jack"
+        assert classes[0].teachers[0].category.name == "Domestic"