implement response check (aio-libs#3892)

* implement response check, aio-libs#3864

* switch to raise_for_status coroutine

* fix linting

* revert name corrections

* fix types, add request tests

* change and docs

* allow non callable truey raise_for_status

CHANGES/3892.feature

@@ -0,0 +1 @@
+allow ``raise_for_status`` to be a coroutine

aiohttp/client.py

@@ -11,6 +11,8 @@
 from types import SimpleNamespace, TracebackType
 from typing import (  # noqa
     Any,
+    Awaitable,
+    Callable,
     Coroutine,
     Generator,
     Generic,
@@ -194,7 +196,7 @@ def __init__(self, *, connector: Optional[BaseConnector]=None,
                  version: HttpVersion=http.HttpVersion11,
                  cookie_jar: Optional[AbstractCookieJar]=None,
                  connector_owner: bool=True,
-                 raise_for_status: bool=False,
+                 raise_for_status: Union[bool, Callable[[ClientResponse], Awaitable[None]]]=False,  # noqa
                  read_timeout: Union[float, object]=sentinel,
                  conn_timeout: Optional[float]=None,
                  timeout: Union[object, ClientTimeout]=sentinel,
@@ -336,7 +338,7 @@ async def _request(
             compress: Optional[str]=None,
             chunked: Optional[bool]=None,
             expect100: bool=False,
-            raise_for_status: Optional[bool]=None,
+            raise_for_status: Union[None, bool, Callable[[ClientResponse], Awaitable[None]]]=None,  # noqa
             read_until_eof: bool=True,
             proxy: Optional[StrOrURL]=None,
             proxy_auth: Optional[BasicAuth]=None,
@@ -584,7 +586,12 @@ async def _request(
             # check response status
             if raise_for_status is None:
                 raise_for_status = self._raise_for_status
-            if raise_for_status:
+
+            if raise_for_status is None:
+                pass
+            elif callable(raise_for_status):
+                await raise_for_status(resp)
+            elif raise_for_status:
                 resp.raise_for_status()
 
             # register connection

docs/client_reference.rst

@@ -128,6 +128,22 @@ The client session supports the context manager protocol for self closing.
       requests where you need to handle responses with status 400 or
       higher.
 
+      You can also provide a coroutine which takes the response as an
+      argument and can raise an exception based on custom logic, e.g.::
+
+          async def custom_check(response):
+              if response.status not in {201, 202}:
+                  raise RuntimeError('expected either 201 or 202')
+              text = await response.text()
+              if 'apple pie' not in text:
+                  raise RuntimeError('I wanted to see "apple pie" in response')
+
+          client_session = aiohttp.ClientSession(raise_for_status=custom_check)
+          ...
+
+      As with boolean values, you're free to set this on the session and/or
+      overwrite it on a per-request basis.
+
    :param timeout: a :class:`ClientTimeout` settings structure, 5min
         total timeout by default.
 

tests/test_client_functional.py

@@ -2333,6 +2333,56 @@ async def handler(request):
             assert False, "never executed"  # pragma: no cover
 
 
+async def test_session_raise_for_status_coro(aiohttp_client) -> None:
+
+    async def handle(request):
+        return web.Response(text='ok')
+
+    app = web.Application()
+    app.router.add_route('GET', '/', handle)
+
+    raise_for_status_called = 0
+
+    async def custom_r4s(response):
+        nonlocal raise_for_status_called
+        raise_for_status_called += 1
+        assert response.status == 200
+        assert response.request_info.method == 'GET'
+
+    client = await aiohttp_client(app, raise_for_status=custom_r4s)
+    await client.get('/')
+    assert raise_for_status_called == 1
+    await client.get('/', raise_for_status=True)
+    assert raise_for_status_called == 1  # custom_r4s not called again
+    await client.get('/', raise_for_status=False)
+    assert raise_for_status_called == 1  # custom_r4s not called again
+
+
+async def test_request_raise_for_status_coro(aiohttp_client) -> None:
+
+    async def handle(request):
+        return web.Response(text='ok')
+
+    app = web.Application()
+    app.router.add_route('GET', '/', handle)
+
+    raise_for_status_called = 0
+
+    async def custom_r4s(response):
+        nonlocal raise_for_status_called
+        raise_for_status_called += 1
+        assert response.status == 200
+        assert response.request_info.method == 'GET'
+
+    client = await aiohttp_client(app)
+    await client.get('/', raise_for_status=custom_r4s)
+    assert raise_for_status_called == 1
+    await client.get('/', raise_for_status=True)
+    assert raise_for_status_called == 1  # custom_r4s not called again
+    await client.get('/', raise_for_status=False)
+    assert raise_for_status_called == 1  # custom_r4s not called again
+
+
 async def test_invalid_idna() -> None:
     session = aiohttp.ClientSession()
     try: