async def METHOD_NAME():
    request_token = {'oauth_token': '1', 'oauth_token_secret': '2'}
    async def assert_func(request):
        auth_header = request.headers.get('authorization')
        assert 'oauth_consumer_key="id"' in auth_header
        assert 'oauth_signature=' in auth_header
    app = AsyncMockDispatch(request_token, assert_func=assert_func)
    async with AsyncOAuth1Client('id', 'secret', app=app) as client:
        response = await client.fetch_request_token(oauth_url)
    assert response == request_token