support django 2.1+ test client json data automatically serialized

docs/api-guide/testing.md

@@ -25,9 +25,12 @@ The `APIRequestFactory` class supports an almost identical API to Django's stand
     factory = APIRequestFactory()
     request = factory.post('/notes/', {'title': 'new idea'})
 
+    # Using the standard RequestFactory API to encode JSON data
+    request = factory.post('/notes/', {'title': 'new idea'}, content_type='application/json')
+
 #### Using the `format` argument
 
-Methods which create a request body, such as `post`, `put` and `patch`, include a `format` argument, which make it easy to generate requests using a content type other than multipart form data.  For example:
+Methods which create a request body, such as `post`, `put` and `patch`, include a `format` argument, which make it easy to generate requests using a wide set of request formats.  When using this argument, the factory will select an appropriate renderer and its configured `content_type`.  For example:
 
     # Create a JSON POST request
     factory = APIRequestFactory()
@@ -41,7 +44,7 @@ To support a wider set of request formats, or change the default format, [see th
 
 If you need to explicitly encode the request body, you can do so by setting the `content_type` flag.  For example:
 
-    request = factory.post('/notes/', json.dumps({'title': 'new idea'}), content_type='application/json')
+    request = factory.post('/notes/', yaml.dump({'title': 'new idea'}), content_type='application/yaml')
 
 #### PUT and PATCH with form data
 

rest_framework/test.py

@@ -151,14 +151,19 @@ 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 ('', content_type)
-
         assert format is None or content_type is None, (
             'You may not set both `format` and `content_type`.'
         )
 
         if content_type:
+            try:
+                data = self._encode_json(data, content_type)
+            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)
 
@@ -176,7 +181,6 @@ 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
@@ -185,6 +189,11 @@ 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 +8,9 @@
 from django.test import TestCase, override_settings
 from django.urls import path
 
-from rest_framework import fields, serializers
+from rest_framework import fields, parsers, serializers
 from rest_framework.authtoken.models import Token
-from rest_framework.decorators import api_view
+from rest_framework.decorators import api_view, parser_classes
 from rest_framework.response import Response
 from rest_framework.test import (
     APIClient, APIRequestFactory, URLPatternsTestCase, force_authenticate
@@ -50,6 +50,12 @@ class BasicSerializer(serializers.Serializer):
     flag = fields.BooleanField(default=lambda: True)
 
 
+@api_view(['POST'])
+@parser_classes((parsers.JSONParser,))
+def post_json_view(request):
+    return Response(request.data)
+
+
 @api_view(['POST'])
 def post_view(request):
     serializer = BasicSerializer(data=request.data)
@@ -62,7 +68,8 @@ def post_view(request):
     path('session-view/', session_view),
     path('redirect-view/', redirect_view),
     path('redirect-view/<int:code>/', redirect_307_308_view),
-    path('post-view/', post_view)
+    path('post-json-view/', post_json_view),
+    path('post-view/', post_view),
 ]
 
 
@@ -236,6 +243,17 @@ def test_empty_post_uses_default_boolean_value(self):
         assert response.status_code == 200
         assert response.data == {"flag": True}
 
+    def test_post_encodes_data_based_on_json_content_type(self):
+        data = {'data': True}
+        response = self.client.post(
+            '/post-json-view/',
+            data=data,
+            content_type='application/json'
+        )
+
+        assert response.status_code == 200
+        assert response.data == data
+
 
 class TestAPIRequestFactory(TestCase):
     def test_csrf_exempt_by_default(self):