Enable test for django-rest-framework serializer

Author: atodorov

.travis.yml

@@ -8,7 +8,7 @@ env:
   - DJANGO="2.0,<3.0"
 
 install:
-  - pip install coverage coveralls
+  - pip install coverage coveralls djangorestframework
   - pip install "Django>=$DJANGO"
   - pip install git+https://github.com/landscapeio/pylint-plugin-utils.git@master
 script:

test/external_drf/func_noerror_serializer.py renamed to test/input/external_drf_noerror_serializer.py

@@ -8,4 +8,3 @@
 class TestSerializerSubclass(serializers.ModelSerializer):
     class Meta:
         pass
-

test/input/external_drf_noerror_serializer.rc

@@ -0,0 +1,2 @@
+[testoptions]
+requires = rest_framework