no body and content length to 0 when 304 response is returned

sanic/response.py

@@ -198,7 +198,7 @@ def output(
 
         body = b''
         content_length = 0
-        if self.status is not 204:
+        if self.status is not 204 and self.status != 304:
             body = self.body
             content_length = self.headers.get('Content-Length', len(self.body))
 

tests/test_response.py

@@ -67,6 +67,14 @@ async def test(request):
     async def no_content_handler(request):
         return json(JSON_DATA, status=204)
 
+    @app.get("/no-content/unmodified")
+    async def no_content_unmodified_handler(request):
+        return json(None, status=304)
+
+    @app.get("/unmodified")
+    async def unmodified_handler(request):
+        return json(JSON_DATA, status=304)
+
     @app.delete("/")
     async def delete_handler(request):
         return json(None, status=204)
@@ -88,6 +96,16 @@ def test_no_content(json_app):
     assert response.text == ''
     assert response.headers['Content-Length'] == '0'
 
+    request, response = json_app.test_client.get('/no-content/unmodified')
+    assert response.status == 304
+    assert response.text == ''
+    assert response.headers['Content-Length'] == '0'
+
+    request, response = json_app.test_client.get('/unmodified')
+    assert response.status == 304
+    assert response.text == ''
+    assert response.headers['Content-Length'] == '0'
+
     request, response = json_app.test_client.delete('/')
     assert response.status == 204
     assert response.text == ''