Deprecate custom router (#3021)

CHANGES/3021.removal

@@ -0,0 +1 @@
+Deprecate custom application's router.

aiohttp/web_app.py

@@ -37,6 +37,9 @@ def __init__(self, *,
                  debug=...):
         if router is None:
             router = UrlDispatcher()
+        else:
+            warnings.warn("router argument is deprecated", DeprecationWarning,
+                          stacklevel=2)
         assert isinstance(router, AbstractRouter), router
 
         if loop is not None:

docs/web_reference.rst

@@ -1243,6 +1243,11 @@ duplicated like one using :meth:`Application.copy`.
                   creates :class:`UrlDispatcher` by default if
                   *router* is ``None``.
 
+      .. deprecated:: 3.3
+
+         The custom routers support is deprecated, the parameter will
+         be removed in 4.0.
+
    :param middlewares: :class:`list` of middleware factories, see
                        :ref:`aiohttp-web-middlewares` for details.
 

tests/test_web_app.py

@@ -132,7 +132,8 @@ async def cb(app):
 
 def test_non_default_router():
     router = mock.Mock(spec=AbstractRouter)
-    app = web.Application(router=router)
+    with pytest.warns(DeprecationWarning):
+        app = web.Application(router=router)
     assert router is app.router
 
 

tests/test_web_urldispatcher.py

@@ -311,7 +311,8 @@ class MyRouter(abc.AbstractRouter):
         async def resolve(self, request):
             raise web.HTTPPreconditionFailed()
 
-    app = web.Application(router=MyRouter())
+    with pytest.warns(DeprecationWarning):
+        app = web.Application(router=MyRouter())
 
     client = await aiohttp_client(app)