fix content length mismatch in windows and other platform

The current implementation of `sanic` attempts to make use of `ujson` if
it's available in the system and if not, it will default to the inbuilt
`json` module provided by python.

The current implementation of `ujson` does not provide a mechanism to
provide a custom `seperators` parameter as part of the `dumps` method
invocation and the default behavior of the module is to strip all the
spaces around seperators such as `:` and `,`. This leads to an
inconsistency in the response length when the response is generated
using the `ujson` and in built `json` module provided by python.

To maintain the consistency, this commit overrides the default behavior
of the `dumps` method provided by the `json` module to add a `seperators`
argument that will strip the white spaces around these character like
the default behavior of `ujson`

This addresses the issue referenced in #1398

Signed-off-by: Harsha Narayana <harsha2k4@gmail.com>

sanic/response.py

@@ -1,3 +1,4 @@
+from functools import partial
 from mimetypes import guess_type
 from os import path
 from urllib.parse import quote_plus
@@ -12,7 +13,11 @@ from sanic.helpers import STATUS_CODES, has_message_body, remove_entity_headers
 try:
     from ujson import dumps as json_dumps
 except BaseException:
-    from json import dumps as json_dumps
+    from json import dumps
+
+    # This is done in order to ensure that the JSON response is
+    # kept consistent across both ujson and inbuilt json usage.
+    json_dumps = partial(dumps, separators=(",", ":"))
 
 
 class BaseHTTPResponse:

tests/test_response.py

@@ -1,20 +1,19 @@
-import sys
 import asyncio
 import inspect
 import os
-from aiofiles import os as async_os
 from mimetypes import guess_type
+from random import choice
+from unittest.mock import MagicMock
 from urllib.parse import unquote
 
 import pytest
-from random import choice
+from aiofiles import os as async_os
 
 from sanic.response import (
     HTTPResponse, stream, StreamingHTTPResponse, file, file_stream, json
 )
 from sanic.server import HttpProtocol
 from sanic.testing import HOST, PORT
-from unittest.mock import MagicMock
 
 JSON_DATA = {'ok': True}
 
@@ -38,7 +37,6 @@ async def sample_streaming_fn(response):
 
 
 def test_method_not_allowed(app):
-
     @app.get('/')
     async def test_get(request):
         return response.json({'hello': 'world'})
@@ -55,12 +53,12 @@ def test_method_not_allowed(app):
 
     request, response = app.test_client.head('/')
     assert response.status == 405
-    assert set(response.headers['Allow'].split(', ')) == set(['GET', 'POST'])
+    assert set(response.headers['Allow'].split(', ')) == {'GET', 'POST'}
     assert response.headers['Content-Length'] == '0'
 
     request, response = app.test_client.patch('/')
     assert response.status == 405
-    assert set(response.headers['Allow'].split(', ')) == set(['GET', 'POST'])
+    assert set(response.headers['Allow'].split(', ')) == {'GET', 'POST'}
     assert response.headers['Content-Length'] == '0'
 
 
@@ -74,15 +72,11 @@ def test_response_header(app):
             'CONTENT-TYPE': 'application/json'
         })
 
-    is_windows = sys.platform in ['win32', 'cygwin']
     request, response = app.test_client.get('/')
     assert dict(response.headers) == {
         'Connection': 'keep-alive',
         'Keep-Alive': str(app.config.KEEP_ALIVE_TIMEOUT),
-        # response body contains an extra \r at the end if its windows
+        'Content-Length': '11',
-        # TODO: this is the only place this difference shows up in our tests
-        # we should figure out a way to unify testing on both platforms
-        'Content-Length': '12' if is_windows else '11',
         'Content-Type': 'application/json',
     }