fix run_app typing (#4957) (#5114)

Co-authored-by: Andrew Svetlov <andrew.svetlov@gmail.com>

CHANGES/4957.bugfix

@@ -0,0 +1 @@
+Fix run_app typing

aiohttp/web.py

@@ -5,7 +5,18 @@
 from argparse import ArgumentParser
 from collections.abc import Iterable
 from importlib import import_module
-from typing import Any, Awaitable, Callable, List, Optional, Set, Type, Union, cast
+from typing import (
+    Any as Any,
+    Awaitable as Awaitable,
+    Callable as Callable,
+    Iterable as TypingIterable,
+    List as List,
+    Optional as Optional,
+    Set as Set,
+    Type as Type,
+    Union as Union,
+    cast as cast,
+)
 
 from .abc import AbstractAccessLogger
 from .helpers import all_tasks
@@ -270,11 +281,13 @@
 except ImportError:  # pragma: no cover
     SSLContext = Any  # type: ignore
 
+HostSequence = TypingIterable[str]
+
 
 async def _run_app(
     app: Union[Application, Awaitable[Application]],
     *,
-    host: Optional[str] = None,
+    host: Optional[Union[str, HostSequence]] = None,
     port: Optional[int] = None,
     path: Optional[str] = None,
     sock: Optional[socket.socket] = None,
@@ -447,7 +460,7 @@ def _cancel_tasks(
 def run_app(
     app: Union[Application, Awaitable[Application]],
     *,
-    host: Optional[str] = None,
+    host: Optional[Union[str, HostSequence]] = None,
     port: Optional[int] = None,
     path: Optional[str] = None,
     sock: Optional[socket.socket] = None,

tests/test_run_app.py

@@ -459,6 +459,27 @@ def test_run_app_nondefault_host_port(patched_loop, aiohttp_unused_port) -> None
     )
 
 
+def test_run_app_multiple_hosts(patched_loop) -> None:
+    hosts = ("127.0.0.1", "127.0.0.2")
+
+    app = web.Application()
+    web.run_app(app, host=hosts, print=stopper(patched_loop))
+
+    calls = map(
+        lambda h: mock.call(
+            mock.ANY,
+            h,
+            8080,
+            ssl=None,
+            backlog=128,
+            reuse_address=None,
+            reuse_port=None,
+        ),
+        hosts,
+    )
+    patched_loop.create_server.assert_has_calls(calls)
+
+
 def test_run_app_custom_backlog(patched_loop) -> None:
     app = web.Application()
     web.run_app(app, backlog=10, print=stopper(patched_loop))