[DONT MERGE, DEMONSTRATION ONLY] Http exceptions refactoring

aiohttp/web_exceptions.py

@@ -66,22 +66,22 @@
 # HTTP Exceptions
 ############################################################
 
-class HTTPException(Response, Exception):
+class HTTPException(Exception):
 
     # You should set in subclasses:
     # status = 200
 
     status_code = None
     empty_body = False
 
-    def __init__(self, *, headers=None, reason=None,
-                 body=None, text=None, content_type=None):
-        Response.__init__(self, status=self.status_code,
-                          headers=headers, reason=reason,
-                          body=body, text=text, content_type=content_type)
-        Exception.__init__(self, self.reason)
-        if self.body is None and not self.empty_body:
-            self.text = "{}: {}".format(self.status, self.reason)
+    def build_response(self):
+        if self.status_code is None:
+            raise RuntimeError("Cannot build abstract HTTP exception: "
+                               "status is not set.")
+        resp = Response(status=self.status_code)
+        if not self.empty_body:
+            resp.text = "{}: {}".format(resp.status, resp.reason)
+        return resp
 
 
 class HTTPError(HTTPException):
@@ -133,15 +133,17 @@ class HTTPPartialContent(HTTPSuccessful):
 
 class _HTTPMove(HTTPRedirection):
 
-    def __init__(self, location, *, headers=None, reason=None,
-                 body=None, text=None, content_type=None):
+    def __init__(self, location):
         if not location:
             raise ValueError("HTTP redirects need a location to redirect to.")
-        super().__init__(headers=headers, reason=reason,
-                         body=body, text=text, content_type=content_type)
-        self.headers['Location'] = str(location)
+        super().__init__()
         self.location = location
 
+    def build_response(self):
+        resp = super().build_response()
+        resp.headers['Location'] = str(self.location)
+        return resp
+
 
 class HTTPMultipleChoices(_HTTPMove):
     status_code = 300
@@ -212,15 +214,17 @@ class HTTPNotFound(HTTPClientError):
 class HTTPMethodNotAllowed(HTTPClientError):
     status_code = 405
 
-    def __init__(self, method, allowed_methods, *, headers=None, reason=None,
-                 body=None, text=None, content_type=None):
-        allow = ','.join(sorted(allowed_methods))
-        super().__init__(headers=headers, reason=reason,
-                         body=body, text=text, content_type=content_type)
-        self.headers['Allow'] = allow
+    def __init__(self, method, allowed_methods):
+        super().__init__()
+        self.allow = ','.join(sorted(allowed_methods))
         self.allowed_methods = allowed_methods
         self.method = method.upper()
 
+    def build_response(self):
+        resp = super().build_response()
+        resp.headers['Allow'] = self.allow
+        return resp
+
 
 class HTTPNotAcceptable(HTTPClientError):
     status_code = 406
@@ -301,13 +305,15 @@ class HTTPRequestHeaderFieldsTooLarge(HTTPClientError):
 class HTTPUnavailableForLegalReasons(HTTPClientError):
     status_code = 451
 
-    def __init__(self, link, *, headers=None, reason=None,
-                 body=None, text=None, content_type=None):
-        super().__init__(headers=headers, reason=reason,
-                         body=body, text=text, content_type=content_type)
-        self.headers['Link'] = '<%s>; rel="blocked-by"' % link
+    def __init__(self, link):
+        super().__init__()
         self.link = link
 
+    def build_response(self):
+        resp = super().build_response()
+        resp.headers['Link'] = '<%s>; rel="blocked-by"' % self.link
+        return resp
+
 
 ############################################################
 # 5xx Server Error

aiohttp/web_middlewares.py

@@ -74,7 +74,7 @@ async def normalize_path_middleware(request, handler):
                 resolves, request = await _check_request_resolves(
                     request, path)
                 if resolves:
-                    return redirect_class(request.path + query)
+                    raise redirect_class(request.path + query)
 
         return (await handler(request))
 

aiohttp/web_protocol.py

@@ -403,7 +403,7 @@ async def start(self, message, payload, handler):
                 try:
                     resp = await self._request_handler(request)
                 except HTTPException as exc:
-                    resp = exc
+                    resp = exc.build_response()
                 except asyncio.CancelledError:
                     self.log_debug('Ignored premature client disconnection')
                     break

aiohttp/web_urldispatcher.py

@@ -218,8 +218,9 @@ def http_exception(self):
         return self._exception
 
     def __repr__(self):
-        return "<MatchInfoError {}: {}>".format(self._exception.status,
-                                                self._exception.reason)
+        resp = self._exception.build_response()
+        return "<MatchInfoError {}: {}>".format(resp.status,
+                                                resp.reason)
 
 
 async def _defaultExpectHandler(request):
@@ -233,7 +234,8 @@ async def _defaultExpectHandler(request):
         if expect.lower() == "100-continue":
             request.writer.write(b"HTTP/1.1 100 Continue\r\n\r\n", drain=False)
         else:
-            raise HTTPExpectationFailed(text="Unknown Expect: %s" % expect)
+            return HTTPExpectationFailed(
+                text="Unknown Expect: %s" % expect).build_response()
 
 
 class Resource(AbstractResource):

aiohttp/web_ws.py

@@ -111,7 +111,7 @@ def _pre_start(self, request):
         except HttpProcessingError as err:
             if err.code == 405:
                 raise HTTPMethodNotAllowed(
-                    request.method, [hdrs.METH_GET], body=b'')
+                    request.method, [hdrs.METH_GET])
             elif err.code == 400:
                 raise HTTPBadRequest(text=err.message, headers=err.headers)
             else:  # pragma: no cover

tests/test_classbasedview.py

@@ -36,8 +36,9 @@ async def get(self):
     request.method = 'UNKNOWN'
     with pytest.raises(web.HTTPMethodNotAllowed) as ctx:
         await MyView(request)
-    assert ctx.value.headers['allow'] == 'GET,OPTIONS'
-    assert ctx.value.status == 405
+    resp = ctx.value.build_response()
+    assert resp.headers['allow'] == 'GET,OPTIONS'
+    assert resp.status == 405
 
 
 async def test_render_unsupported_method():
@@ -51,5 +52,6 @@ async def get(self):
     request.method = 'POST'
     with pytest.raises(web.HTTPMethodNotAllowed) as ctx:
         await MyView(request)
-    assert ctx.value.headers['allow'] == 'DELETE,GET,OPTIONS'
-    assert ctx.value.status == 405
+    resp = ctx.value.build_response()
+    assert resp.headers['allow'] == 'DELETE,GET,OPTIONS'
+    assert resp.status == 405