From af53fe00b1a7e09ca1173b56169c40047700fa0e Mon Sep 17 00:00:00 2001
From: Andrew Svetlov <andrew.svetlov@gmail.com>
Date: Thu, 24 May 2018 10:58:25 +0300
Subject: [PATCH] Deprecate custom router (#3021)

---
 CHANGES/3021.removal            | 1 +
 aiohttp/web_app.py              | 3 +++
 docs/web_reference.rst          | 5 +++++
 tests/test_web_app.py           | 3 ++-
 tests/test_web_urldispatcher.py | 3 ++-
 5 files changed, 13 insertions(+), 2 deletions(-)
 create mode 100644 CHANGES/3021.removal

diff --git a/CHANGES/3021.removal b/CHANGES/3021.removal
new file mode 100644
index 00000000000..ea54a0f0e3d
--- /dev/null
+++ b/CHANGES/3021.removal
@@ -0,0 +1 @@
+Deprecate custom application's router.
\ No newline at end of file
diff --git a/aiohttp/web_app.py b/aiohttp/web_app.py
index a808b06f917..a1a8a817599 100644
--- a/aiohttp/web_app.py
+++ b/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:
diff --git a/docs/web_reference.rst b/docs/web_reference.rst
index 2f60dd5abd5..e1cf79f7bc9 100644
--- a/docs/web_reference.rst
+++ b/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.
 
diff --git a/tests/test_web_app.py b/tests/test_web_app.py
index dd2ec2f7809..f210ed40e50 100644
--- a/tests/test_web_app.py
+++ b/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
 
 
diff --git a/tests/test_web_urldispatcher.py b/tests/test_web_urldispatcher.py
index 5deefcf6708..9a83dadc7f9 100644
--- a/tests/test_web_urldispatcher.py
+++ b/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)