Testing PUT method in Django Rest Framework

I'm trying to test a PUT method in django rest framework. I get HttpResponsePermanentRedirect instead of response object. My views for a put method are set to send status 200 after successful update.
Error:
self.assertEqual(response.data, serializer.data) AttributeError: 'HttpResponsePermanentRedirect' object has no attribute 'data'

tests.py

class PostTestGetAndPutMethod(APITestCase):
    def setup(self):
        Post.objects.create(title="POST CREATED", content="POST WAS CREATED")
        Post.objects.create(title="POST CREATED 2", content="POST WAS CREATED 2")
        Post.objects.create(title="POST CREATED 3", content="POST WAS CREATED 3")

    def test_get_posts(self):
        '''
        Ensure we can get list of posts
        '''
        # get API response 
        response = self.client.get(reverse('posts'))
        # get data from DB
        posts = Post.objects.all()
        # convert it to JSON
        serializer = PostSerializer(posts, many=True)
        # check the status 
        self.assertEqual(response.status_code, status.HTTP_200_OK)
        self.assertEqual(response.data, serializer.data)

    def test_update_put_post(self):
        '''
        Check if we can update post 
        '''
        data = {'title': 'POST MODIFIED', 'content': 'CONTENT MODIFIED'}
        response = self.client.put('/posts/1', data)
        serializer = PostSerializer(data)
        self.assertEqual(response.data, serializer.data)
        self.assertEqual(response.status_code, status.HTTP_200_OK)

views.py

@api_view(['GET', 'PUT', 'DELETE'])
def post_detail(request, pk):
    """
    Retrieve, update or delete a code snippet.
    """
    try:
        post = Post.objects.get(pk=pk)
    except Post.DoesNotExist:
        return Response(status=status.HTTP_404_NOT_FOUND)

    if request.method == 'GET':
        serializer = PostSerializer(post)
        return Response(data=serializer.data, status=status.HTTP_200_OK)

    elif request.method == 'PUT':
        serializer = PostSerializer(post, data=data)
        if serializer.is_valid():
            serializer.save()
            return Response(serializer.data, status=status.HTTP_200_OK)
        return Response(serializer.errors, status=status.HTTP_400_BAD_REQUEST)

    elif request.method == 'DELETE':
        post.delete()
        return Response(status=status.HTTP_204_NO_CONTENT)