Testing

Testing aiohttp web servers

aiohttp provides plugin for pytest making writing web server tests extremely easy, it also provides test framework agnostic utilities for testing with other frameworks such as unittest.

Before starting to write your tests, you may also be interested on reading how to write testable services that interact with the loop.

For using pytest plugin please install pytest-aiohttp library:

$ pip install pytest-aiohttp

If you don’t want to install pytest-aiohttp for some reason you may insert pytest_plugins = 'aiohttp.pytest_plugin' line into conftest.py instead for the same functionality.

Provisional Status

The module is a provisional.

aiohttp has a year and half period for removing deprecated API (Policy for Backward Incompatible Changes).

But for aiohttp.test_tools the deprecation period could be reduced.

Moreover we may break backward compatibility without deprecation period for some very strong reason.

The Test Client and Servers

aiohttp test utils provides a scaffolding for testing aiohttp-based web servers.

They are consist of two parts: running test server and making HTTP requests to this server.

TestServer runs aiohttp.web.Application based server, RawTestServer starts aiohttp.web.WebServer low level server.

For performing HTTP requests to these servers you have to create a test client: TestClient instance.

The client incapsulates aiohttp.ClientSession by providing proxy methods to the client for common operations such as ws_connect, get, post, etc.

Pytest

The aiohttp_client fixture available from pytest-aiohttp plugin allows you to create a client to make requests to test your app.

A simple would be:

from aiohttp import web

async def hello(request):
    return web.Response(text='Hello, world')

async def test_hello(aiohttp_client, loop):
    app = web.Application()
    app.router.add_get('/', hello)
    client = await aiohttp_client(app)
    resp = await client.get('/')
    assert resp.status == 200
    text = await resp.text()
    assert 'Hello, world' in text

It also provides access to the app instance allowing tests to check the state of the app. Tests can be made even more succinct with a fixture to create an app test client:

import pytest
from aiohttp import web


async def previous(request):
    if request.method == 'POST':
        request.app['value'] = (await request.post())['value']
        return web.Response(body=b'thanks for the data')
    return web.Response(
        body='value: {}'.format(request.app['value']).encode('utf-8'))

@pytest.fixture
def cli(loop, aiohttp_client):
    app = web.Application()
    app.router.add_get('/', previous)
    app.router.add_post('/', previous)
    return loop.run_until_complete(aiohttp_client(app))

async def test_set_value(cli):
    resp = await cli.post('/', data={'value': 'foo'})
    assert resp.status == 200
    assert await resp.text() == 'thanks for the data'
    assert cli.server.app['value'] == 'foo'

async def test_get_value(cli):
    cli.server.app['value'] = 'bar'
    resp = await cli.get('/')
    assert resp.status == 200
    assert await resp.text() == 'value: bar'

Pytest tooling has the following fixtures:

aiohttp.test_utils.aiohttp_server(app, *, port=None, **kwargs)

A fixture factory that creates TestServer:

async def test_f(aiohttp_server):
    app = web.Application()
    # fill route table

    server = await aiohttp_server(app)

The server will be destroyed on exit from test function.

app is the aiohttp.web.Application used
to start server.

port optional, port the server is run at, if not provided a random unused port is used.

New in version 3.0.

kwargs are parameters passed to
aiohttp.web.Application.make_handler()

Changed in version 3.0.

Deprecated since version 3.2: The fixture was renamed from test_server to aiohttp_server.

aiohttp.test_utils.aiohttp_client(app, server_kwargs=None, **kwargs)
aiohttp.test_utils.aiohttp_client(server, **kwargs)
aiohttp.test_utils.aiohttp_client(raw_server, **kwargs)

A fixture factory that creates TestClient for access to tested server:

async def test_f(aiohttp_client):
    app = web.Application()
    # fill route table

    client = await aiohttp_client(app)
    resp = await client.get('/')

client and responses are cleaned up after test function finishing.

The fixture accepts aiohttp.web.Application, aiohttp.test_utils.TestServer or aiohttp.test_utils.RawTestServer instance.

server_kwargs are parameters passed to the test server if an app is passed, else ignored.

kwargs are parameters passed to aiohttp.test_utils.TestClient constructor.

Changed in version 3.0: The fixture was renamed from test_client to aiohttp_client.

aiohttp.test_utils.aiohttp_raw_server(handler, *, port=None, **kwargs)

A fixture factory that creates RawTestServer instance from given web handler.:

async def test_f(aiohttp_raw_server, aiohttp_client):

    async def handler(request):
        return web.Response(text="OK")

    raw_server = await aiohttp_raw_server(handler)
    client = await aiohttp_client(raw_server)
    resp = await client.get('/')

handler should be a coroutine which accepts a request and returns response, e.g.

port optional, port the server is run at, if not provided a random unused port is used.

New in version 3.0.

aiohttp.test_utils.aiohttp_unused_port

Function to return an unused port number for IPv4 TCP protocol:

async def test_f(aiohttp_client, aiohttp_unused_port):
    port = aiohttp_unused_port()
    app = web.Application()
    # fill route table

    client = await aiohttp_client(app, server_kwargs={'port': port})
    ...

Changed in version 3.0: The fixture was renamed from unused_port to aiohttp_unused_port.

Unittest

To test applications with the standard library’s unittest or unittest-based functionality, the AioHTTPTestCase is provided:

from aiohttp.test_utils import AioHTTPTestCase, unittest_run_loop
from aiohttp import web

class MyAppTestCase(AioHTTPTestCase):

    async def get_application(self):
        """
        Override the get_app method to return your application.
        """
        async def hello(request):
            return web.Response(text='Hello, world')

        app = web.Application()
        app.router.add_get('/', hello)
        return app

    # the unittest_run_loop decorator can be used in tandem with
    # the AioHTTPTestCase to simplify running
    # tests that are asynchronous
    @unittest_run_loop
    async def test_example(self):
        resp = await self.client.request("GET", "/")
        assert resp.status == 200
        text = await resp.text()
        assert "Hello, world" in text

    # a vanilla example
    def test_example_vanilla(self):
        async def test_get_route():
            url = "/"
            resp = await self.client.request("GET", url)
            assert resp.status == 200
            text = await resp.text()
            assert "Hello, world" in text

        self.loop.run_until_complete(test_get_route())
class aiohttp.test_utils.AioHTTPTestCase

A base class to allow for unittest web applications using aiohttp.

Derived from unittest.TestCase

Provides the following:

client

an aiohttp test client, TestClient instance.

server

an aiohttp test server, TestServer instance.

New in version 2.3.

loop

The event loop in which the application and server are running.

app

The application returned by get_app() (aiohttp.web.Application instance).

coroutine get_client()

This async method can be overridden to return the TestClient object used in the test.

Returns:TestClient instance.

New in version 2.3.

coroutine get_server()

This async method can be overridden to return the TestServer object used in the test.

Returns:TestServer instance.

New in version 2.3.

coroutine get_application()

This async method should be overridden to return the aiohttp.web.Application object to test.

Returns:aiohttp.web.Application instance.
coroutine setUpAsync()

This async method do nothing by default and can be overridden to execute asynchronous code during the setUp stage of the TestCase.

New in version 2.3.

coroutine tearDownAsync()

This async method do nothing by default and can be overridden to execute asynchronous code during the tearDown stage of the TestCase.

New in version 2.3.

setUp()

Standard test initialization method.

tearDown()

Standard test finalization method.

Note

The TestClient’s methods are asynchronous: you have to execute function on the test client using asynchronous methods.

A basic test class wraps every test method by unittest_run_loop() decorator:

class TestA(AioHTTPTestCase):

    @unittest_run_loop
    async def test_f(self):
        resp = await self.client.get('/')
unittest_run_loop:

A decorator dedicated to use with asynchronous methods of an AioHTTPTestCase.

Handles executing an asynchronous function, using the AioHTTPTestCase.loop of the AioHTTPTestCase.

Faking request object

aiohttp provides test utility for creating fake aiohttp.web.Request objects: aiohttp.test_utils.make_mocked_request(), it could be useful in case of simple unit tests, like handler tests, or simulate error conditions that hard to reproduce on real server:

from aiohttp import web
from aiohttp.test_utils import make_mocked_request

def handler(request):
    assert request.headers.get('token') == 'x'
    return web.Response(body=b'data')

def test_handler():
    req = make_mocked_request('GET', '/', headers={'token': 'x'})
    resp = handler(req)
    assert resp.body == b'data'

Warning

We don’t recommend to apply make_mocked_request() everywhere for testing web-handler’s business object – please use test client and real networking via ‘localhost’ as shown in examples before.

make_mocked_request() exists only for testing complex cases (e.g. emulating network errors) which are extremely hard or even impossible to test by conventional way.

aiohttp.test_utils.make_mocked_request(method, path, headers=None, *, version=HttpVersion(1, 1), closing=False, app=None, match_info=sentinel, reader=sentinel, writer=sentinel, transport=sentinel, payload=sentinel, sslcontext=None, loop=...)

Creates mocked web.Request testing purposes.

Useful in unit tests, when spinning full web server is overkill or specific conditions and errors are hard to trigger.

Parameters:
  • method (str) – str, that represents HTTP method, like; GET, POST.
  • path (str) – str, The URL including PATH INFO without the host or scheme
  • headers (dict, multidict.CIMultiDict, list of pairs) – mapping containing the headers. Can be anything accepted by the multidict.CIMultiDict constructor.
  • match_info (dict) – mapping containing the info to match with url parameters.
  • version (aiohttp.protocol.HttpVersion) – namedtuple with encoded HTTP version
  • closing (bool) – flag indicates that connection should be closed after response.
  • app (aiohttp.web.Application) – the aiohttp.web application attached for fake request
  • writer (aiohttp.StreamWriter) – object for managing outcoming data
  • transport (asyncio.transports.Transport) – asyncio transport instance
  • payload (aiohttp.StreamReader) – raw payload reader object
  • sslcontext (ssl.SSLContext) – ssl.SSLContext object, for HTTPS connection
  • loop (asyncio.AbstractEventLoop) – An event loop instance, mocked loop by default.
Returns:

aiohttp.web.Request object.

New in version 2.3: match_info parameter.

Framework Agnostic Utilities

High level test creation:

from aiohttp.test_utils import TestClient, TestServer, loop_context
from aiohttp import request

# loop_context is provided as a utility. You can use any
# asyncio.BaseEventLoop class in it's place.
with loop_context() as loop:
    app = _create_example_app()
    with TestClient(TestServer(app), loop=loop) as client:

        async def test_get_route():
            nonlocal client
            resp = await client.get("/")
            assert resp.status == 200
            text = await resp.text()
            assert "Hello, world" in text

        loop.run_until_complete(test_get_route())

If it’s preferred to handle the creation / teardown on a more granular basis, the TestClient object can be used directly:

from aiohttp.test_utils import TestClient, TestServer

with loop_context() as loop:
    app = _create_example_app()
    client = TestClient(TestSever(app), loop=loop)
    loop.run_until_complete(client.start_server())
    root = "http://127.0.0.1:{}".format(port)

    async def test_get_route():
        resp = await client.get("/")
        assert resp.status == 200
        text = await resp.text()
        assert "Hello, world" in text

    loop.run_until_complete(test_get_route())
    loop.run_until_complete(client.close())

A full list of the utilities provided can be found at the api reference

Testing API Reference

Test server

Runs given aiohttp.web.Application instance on random TCP port.

After creation the server is not started yet, use start_server() for actual server starting and close() for stopping/cleanup.

Test server usually works in conjunction with aiohttp.test_utils.TestClient which provides handy client methods for accessing to the server.

class aiohttp.test_utils.BaseTestServer(*, scheme='http', host='127.0.0.1', port=None)

Base class for test servers.

Parameters:
  • scheme (str) – HTTP scheme, non-protected "http" by default.
  • host (str) – a host for TCP socket, IPv4 local host ('127.0.0.1') by default.
  • port (int) –

    optional port for TCP socket, if not provided a random unused port is used.

    New in version 3.0.
scheme

A scheme for tested application, 'http' for non-protected run and 'https' for TLS encrypted server.

host

host used to start a test server.

port

port used to start the test server.

handler

aiohttp.web.WebServer used for HTTP requests serving.

server

asyncio.AbstractServer used for managing accepted connections.

coroutine start_server(loop=None, **kwargs)
Parameters:loop (asyncio.AbstractEventLoop) – the event_loop to use

Start a test server.

coroutine close()

Stop and finish executed test server.

make_url(path)

Return an absolute URL for given path.

class aiohttp.test_utils.RawTestServer(handler, *, scheme="http", host='127.0.0.1')

Low-level test server (derived from BaseTestServer).

Parameters:
  • handler –

    a coroutine for handling web requests. The handler should accept aiohttp.web.BaseRequest and return a response instance, e.g. StreamResponse or Response.

    The handler could raise HTTPException as a signal for non-200 HTTP response.

  • scheme (str) – HTTP scheme, non-protected "http" by default.
  • host (str) – a host for TCP socket, IPv4 local host ('127.0.0.1') by default.
  • port (int) –

    optional port for TCP socket, if not provided a random unused port is used.

    New in version 3.0.
class aiohttp.test_utils.TestServer(app, *, scheme="http", host='127.0.0.1')

Test server (derived from BaseTestServer) for starting Application.

Parameters:
  • app – aiohttp.web.Application instance to run.
  • scheme (str) – HTTP scheme, non-protected "http" by default.
  • host (str) – a host for TCP socket, IPv4 local host ('127.0.0.1') by default.
  • port (int) –

    optional port for TCP socket, if not provided a random unused port is used.

    New in version 3.0.
app

aiohttp.web.Application instance to run.

Test Client

class aiohttp.test_utils.TestClient(app_or_server, *, loop=None, scheme='http', host='127.0.0.1', cookie_jar=None, **kwargs)

A test client used for making calls to tested server.

Parameters:
  • app_or_server –

    BaseTestServer instance for making client requests to it.

    In order to pass a aiohttp.web.Application you need to convert it first to TestServer first with TestServer(app).

  • cookie_jar – an optional aiohttp.CookieJar instance, may be useful with CookieJar(unsafe=True) option.
  • scheme (str) – HTTP scheme, non-protected "http" by default.
  • loop (asyncio.AbstractEventLoop) – the event_loop to use
  • host (str) – a host for TCP socket, IPv4 local host ('127.0.0.1') by default.
scheme

A scheme for tested application, 'http' for non-protected run and 'https' for TLS encrypted server.

host

host used to start a test server.

port

port used to start the server

server

BaseTestServer test server instance used in conjunction with client.

app

An alias for self.server.app. return None if self.server is not TestServer instance(e.g. RawTestServer instance for test low-level server).

session

An internal aiohttp.ClientSession.

Unlike the methods on the TestClient, client session requests do not automatically include the host in the url queried, and will require an absolute path to the resource.

coroutine start_server(**kwargs)

Start a test server.

coroutine close()

Stop and finish executed test server.

make_url(path)

Return an absolute URL for given path.

coroutine request(method, path, *args, **kwargs)

Routes a request to tested http server.

The interface is identical to aiohttp.ClientSession.request(), except the loop kwarg is overridden by the instance used by the test server.

coroutine get(path, *args, **kwargs)

Perform an HTTP GET request.

coroutine post(path, *args, **kwargs)

Perform an HTTP POST request.

coroutine options(path, *args, **kwargs)

Perform an HTTP OPTIONS request.

coroutine head(path, *args, **kwargs)

Perform an HTTP HEAD request.

coroutine put(path, *args, **kwargs)

Perform an HTTP PUT request.

coroutine patch(path, *args, **kwargs)

Perform an HTTP PATCH request.

coroutine delete(path, *args, **kwargs)

Perform an HTTP DELETE request.

coroutine ws_connect(path, *args, **kwargs)

Initiate websocket connection.

The api corresponds to aiohttp.ClientSession.ws_connect().

Utilities

aiohttp.test_utils.make_mocked_coro(return_value)

Creates a coroutine mock.

Behaves like a coroutine which returns return_value. But it is also a mock object, you might test it as usual Mock:

mocked = make_mocked_coro(1)
assert 1 == await mocked(1, 2)
mocked.assert_called_with(1, 2)
Parameters:return_value – A value that the the mock object will return when called.
Returns:A mock object that behaves as a coroutine which returns return_value when called.
aiohttp.test_utils.unused_port()

Return an unused port number for IPv4 TCP protocol.

Return int:ephemeral port number which could be reused by test server.
aiohttp.test_utils.loop_context(loop_factory=<function asyncio.new_event_loop>)

A contextmanager that creates an event_loop, for test purposes.

Handles the creation and cleanup of a test loop.

aiohttp.test_utils.setup_test_loop(loop_factory=<function asyncio.new_event_loop>)

Create and return an asyncio.AbstractEventLoop instance.

The caller should also call teardown_test_loop, once they are done with the loop.

Note

As side effect the function changes asyncio default loop by asyncio.set_event_loop() call.

Previous default loop is not restored.

It should not be a problem for test suite: every test expects a new test loop instance anyway.

Changed in version 3.1: The function installs a created event loop as default.

aiohttp.test_utils.teardown_test_loop(loop)

Teardown and cleanup an event_loop created by setup_test_loop.

Parameters:loop (asyncio.AbstractEventLoop) – the loop to teardown