Allow empty body without Content-Type; Introduce response.empty() (#1736)

sanic/response.py

@@ -153,7 +153,7 @@ class HTTPResponse(BaseHTTPResponse):
         body=None,
         status=200,
         headers=None,
-        content_type="text/plain",
+        content_type=None,
         body_bytes=b"",
     ):
         self.content_type = content_type
@@ -181,9 +181,9 @@ class HTTPResponse(BaseHTTPResponse):
                 "Content-Length", len(self.body)
             )
 
-        self.headers["Content-Type"] = self.headers.get(
+        # self.headers get priority over content_type
-            "Content-Type", self.content_type
+        if self.content_type and "Content-Type" not in self.headers:
-        )
+            self.headers["Content-Type"] = self.content_type
 
         if self.status in (304, 412):
             self.headers = remove_entity_headers(self.headers)
@@ -214,6 +214,18 @@ class HTTPResponse(BaseHTTPResponse):
         return self._cookies
 
 
+def empty(
+    status=204, headers=None,
+):
+    """
+    Returns an empty response to the client.
+
+    :param status Response code.
+    :param headers Custom Headers.
+    """
+    return HTTPResponse(body_bytes=b"", status=status, headers=headers,)
+
+
 def json(
     body,
     status=200,

tests/test_response.py

@@ -21,6 +21,7 @@ from sanic.response import (
     raw,
     stream,
 )
+from sanic.response import empty
 from sanic.server import HttpProtocol
 from sanic.testing import HOST, PORT
 
@@ -591,3 +592,13 @@ def test_raw_response(app):
     request, response = app.test_client.get("/test")
     assert response.content_type == "application/octet-stream"
     assert response.body == b"raw_response"
+
+
+def test_empty_response(app):
+    @app.get("/test")
+    def handler(request):
+        return empty()
+
+    request, response = app.test_client.get("/test")
+    assert response.content_type is None
+    assert response.body == b""