Fixed regression that tests using format still work (#9615)

* Fixed regression that tests using format still work

Error only occurred on tests which return no content and use
a renderer without charset (e.g. JSONRenderer)

* Fixed linting

* Used early return as before

* Move ret str check back to where it was

rest_framework/test.py

@@ -150,6 +150,8 @@ def _encode_data(self, data, format=None, content_type=None):
         """
         Encode the data returning a two tuple of (bytes, content_type)
         """
+        if data is None:
+            return (b'', content_type)
 
         assert format is None or content_type is None, (
             'You may not set both `format` and `content_type`.'
@@ -161,9 +163,6 @@ def _encode_data(self, data, format=None, content_type=None):
             except AttributeError:
                 pass
 
-            if data is None:
-                data = ''
-
             # Content type specified explicitly, treat data as a raw bytestring
             ret = force_bytes(data, settings.DEFAULT_CHARSET)
 
@@ -181,6 +180,7 @@ def _encode_data(self, data, format=None, content_type=None):
 
             # Use format and render the data into a bytestring
             renderer = self.renderer_classes[format]()
+            ret = renderer.render(data)
 
             # Determine the content-type header from the renderer
             content_type = renderer.media_type
@@ -189,11 +189,6 @@ def _encode_data(self, data, format=None, content_type=None):
                     content_type, renderer.charset
                 )
 
-            if data is None:
-                ret = ''
-            else:
-                ret = renderer.render(data)
-
             # Coerce text to bytes if required.
             if isinstance(ret, str):
                 ret = ret.encode(renderer.charset)

tests/test_testing.py

@@ -8,9 +8,11 @@
 from django.test import TestCase, override_settings
 from django.urls import path
 
-from rest_framework import fields, parsers, serializers
+from rest_framework import fields, parsers, renderers, serializers, status
 from rest_framework.authtoken.models import Token
-from rest_framework.decorators import api_view, parser_classes
+from rest_framework.decorators import (
+    api_view, parser_classes, renderer_classes
+)
 from rest_framework.response import Response
 from rest_framework.test import (
     APIClient, APIRequestFactory, URLPatternsTestCase, force_authenticate
@@ -56,6 +58,12 @@ def post_json_view(request):
     return Response(request.data)
 
 
+@api_view(['DELETE'])
+@renderer_classes((renderers.JSONRenderer, ))
+def delete_json_view(request):
+    return Response(status=status.HTTP_204_NO_CONTENT)
+
+
 @api_view(['POST'])
 def post_view(request):
     serializer = BasicSerializer(data=request.data)
@@ -69,6 +77,7 @@ def post_view(request):
     path('redirect-view/', redirect_view),
     path('redirect-view/<int:code>/', redirect_307_308_view),
     path('post-json-view/', post_json_view),
+    path('delete-json-view/', delete_json_view),
     path('post-view/', post_view),
 ]
 
@@ -254,6 +263,11 @@ def test_post_encodes_data_based_on_json_content_type(self):
         assert response.status_code == 200
         assert response.data == data
 
+    def test_delete_based_on_format(self):
+        response = self.client.delete('/delete-json-view/', format='json')
+        assert response.status_code == status.HTTP_204_NO_CONTENT
+        assert response.data is None
+
 
 class TestAPIRequestFactory(TestCase):
     def test_csrf_exempt_by_default(self):