Use functools.wraps when wrapping synchronous handlers

aiohttp/web_urldispatcher.py

@@ -7,6 +7,7 @@
 import re
 import warnings
 from collections.abc import Container, Iterable, Sized
+from functools import wraps
 from pathlib import Path
 from types import MappingProxyType
 
@@ -106,6 +107,7 @@ def __init__(self, method, handler, *,
               issubclass(handler, AbstractView)):
             pass
         else:
+            @wraps(handler)
             @asyncio.coroutine
             def handler_wrapper(*args, **kwargs):
                 result = old_handler(*args, **kwargs)

tests/test_web_urldispatcher.py

@@ -180,6 +180,30 @@ def handler(_):
     assert r.status == 200
 
 
+@asyncio.coroutine
+def test_handler_metadata_persistence():
+    """
+    Tests accessing metadata of a handler after registering it on the app
+    router.
+    """
+    app = web.Application()
+
+    async def async_handler(_):
+        """Doc"""
+        return web.Response()
+
+    def sync_handler(_):
+        """Doc"""
+        return web.Response()
+
+    app.router.add_get('/async', async_handler)
+    app.router.add_get('/sync', sync_handler)
+
+    for resource in app.router.resources():
+        for route in resource:
+            assert route.handler.__doc__ == 'Doc'
+
+
 @asyncio.coroutine
 def test_unauthorized_folder_access(tmp_dir_path, loop, test_client):
     """