Fixed #24773 -- Added a json() method on test client responses.

docs/topics/testing/tools.txt

@@ -425,6 +425,20 @@ Specifically, a ``Response`` object has the following attributes:
             >>> response.context['name']
             'Arthur'
 
+    .. method:: json(**kwargs)
+
+        .. versionadded:: 1.9
+
+        The body of the response, parsed as JSON. Extra keyword arguments are
+        passed to :func:`json.loads`. For example::
+
+            >>> response = client.get('/foo/')
+            >>> response.json()['name']
+            'Arthur'
+
+        If the ``Content-Type`` header is not ``"application/json"``, then a
+        :exc:`ValueError` will be raised when trying to parse the response.
+
     .. attribute:: request
 
         The request data that stimulated the response.