do not include content-length header in 304

sanic/response.py

@@ -72,7 +72,12 @@ STATUS_CODES = {
     511: b'Network Authentication Required'
 }
 
-EMPTY_STATUS_CODES = [204, 304]
+# These should all have no response body. The True/False indicates if they
+# should also include the content-length header.
+EMPTY_STATUS_CODES = {
+        204: True,
+        304: False
+        }
 
 
 class BaseHTTPResponse:
@@ -198,13 +203,17 @@ class HTTPResponse(BaseHTTPResponse):
         if keep_alive and keep_alive_timeout is not None:
             timeout_header = b'Keep-Alive: %d\r\n' % keep_alive_timeout
 
-        body = b''
-        content_length = 0
-        if self.status not in EMPTY_STATUS_CODES:
         body = self.body
         content_length = self.headers.get('Content-Length', len(self.body))
-
         self.headers['Content-Length'] = content_length
+
+        if self.status in EMPTY_STATUS_CODES:
+            body = b''
+            content_length = 0
+            self.headers['Content-Length'] = content_length
+            if not EMPTY_STATUS_CODES.get(self.status):
+                del self.headers['Content-Length']
+
         self.headers['Content-Type'] = self.headers.get(
             'Content-Type', self.content_type)
 

tests/test_response.py

@@ -99,12 +99,12 @@ def test_no_content(json_app):
     request, response = json_app.test_client.get('/no-content/unmodified')
     assert response.status == 304
     assert response.text == ''
-    assert response.headers['Content-Length'] == '0'
+    assert response.headers.get('Content-Length') == None
 
     request, response = json_app.test_client.get('/unmodified')
     assert response.status == 304
     assert response.text == ''
-    assert response.headers['Content-Length'] == '0'
+    assert response.headers.get('Content-Length') == None
 
     request, response = json_app.test_client.delete('/')
     assert response.status == 204