Pytest async fixtures (#2226)

* Accept async fixtures in pytest plugin (#2223)

* Add tests for async fixtures (#2223)

* Update changelog

* Update CONTRIBUTORS.txt

* Update helpers.py

CONTRIBUTORS.txt

@@ -191,6 +191,7 @@ Will McGugan
 Willem de Groot
 Wilson Ong
 Yannick Koechlin
+Yannick Péroux
 Yegor Roganov
 Young-Ho Cha
 Yuriy Shatrov

aiohttp/helpers.py

@@ -6,6 +6,7 @@
 import cgi
 import datetime
 import functools
+import inspect
 import os
 import re
 import sys
@@ -237,6 +238,12 @@ def current_task(loop=None):
     return task
 
 
+def isasyncgenfunction(obj):
+    if hasattr(inspect, 'isasyncgenfunction'):
+        return inspect.isasyncgenfunction(obj)
+    return False
+
+
 def parse_mimetype(mimetype):
     """Parses a MIME type into its components.
 

aiohttp/pytest_plugin.py

@@ -7,6 +7,7 @@
 import pytest
 from py import path
 
+from aiohttp.helpers import isasyncgenfunction
 from aiohttp.web import Application
 
 from .test_utils import unused_port as _unused_port
@@ -37,6 +38,62 @@ def pytest_addoption(parser):
         help='enable event loop debug mode')
 
 
+def pytest_fixture_setup(fixturedef, request):
+    """
+    Allow fixtures to be coroutines. Run coroutine fixtures in an event loop.
+    """
+    func = fixturedef.func
+
+    if isasyncgenfunction(func):
+        # async generator fixture
+        is_async_gen = True
+    elif asyncio.iscoroutinefunction(func):
+        # regular async fixture
+        is_async_gen = False
+    else:
+        # not an async fixture, nothing to do
+        return
+
+    strip_request = False
+    if 'request' not in fixturedef.argnames:
+        fixturedef.argnames += ('request',)
+        strip_request = True
+
+    def wrapper(*args, **kwargs):
+        request = kwargs['request']
+        if strip_request:
+            del kwargs['request']
+
+        # if neither the fixture nor the test use the 'loop' fixture,
+        # 'getfixturevalue' will fail because the test is not parameterized
+        # (this can be removed someday if 'loop' is no longer parameterized)
+        if 'loop' not in request.fixturenames:
+            raise Exception(
+                "Asynchronous fixtures must depend on the 'loop' fixture or "
+                "be used in tests depending from it."
+            )
+
+        _loop = request.getfixturevalue('loop')
+
+        if is_async_gen:
+            # for async generators, we need to advance the generator once,
+            # then advance it again in a finalizer
+            gen = func(*args, **kwargs)
+
+            def finalizer():
+                try:
+                    return _loop.run_until_complete(gen.__anext__())
+                except StopAsyncIteration:  # NOQA
+                    pass
+
+            request.addfinalizer(finalizer)
+            return _loop.run_until_complete(gen.__anext__())
+        else:
+            return _loop.run_until_complete(func(*args, **kwargs))
+
+    fixturedef.func = wrapper
+
+
 @pytest.fixture
 def fast(request):
     """ --fast config option """

changes/2223.feature

@@ -0,0 +1 @@
+Accept coroutine fixtures in pytest plugin

tests/test_pytest_plugin.py

@@ -3,6 +3,8 @@
 
 import pytest
 
+from aiohttp.pytest_plugin import LOOP_FACTORIES
+
 
 pytest_plugins = 'pytester'
 
@@ -180,3 +182,116 @@ async def test_bad():
     stdout, _ = capsys.readouterr()
     assert ("test_warning_checks.py:__LINE__:coroutine 'foobar' was "
             "never awaited" in re.sub('\d{2,}', '__LINE__', stdout))
+
+
+def test_aiohttp_plugin_async_fixture(testdir, capsys):
+    testdir.makepyfile("""\
+import asyncio
+import pytest
+
+from aiohttp import web
+
+
+pytest_plugins = 'aiohttp.pytest_plugin'
+
+
+@asyncio.coroutine
+def hello(request):
+    return web.Response(body=b'Hello, world')
+
+
+def create_app(loop):
+    app = web.Application()
+    app.router.add_route('GET', '/', hello)
+    return app
+
+
+@pytest.fixture
+@asyncio.coroutine
+def cli(test_client):
+    client = yield from test_client(create_app)
+    return client
+
+
+@pytest.fixture
+@asyncio.coroutine
+def foo():
+    return 42
+
+
+@pytest.fixture
+@asyncio.coroutine
+def bar(request):
+    # request should be accessible in async fixtures if needed
+    return request.function
+
+
+@asyncio.coroutine
+def test_hello(cli):
+    resp = yield from cli.get('/')
+    assert resp.status == 200
+
+
+def test_foo(loop, foo):
+    assert foo == 42
+
+
+def test_foo_without_loop(foo):
+    # will raise an error because there is no loop
+    pass
+
+
+def test_bar(loop, bar):
+    assert bar is test_bar
+""")
+    nb_loops = len(LOOP_FACTORIES)
+    result = testdir.runpytest('-p', 'no:sugar')
+    result.assert_outcomes(passed=3 * nb_loops, error=1)
+    result.stdout.fnmatch_lines(
+        "*Asynchronous fixtures must depend on the 'loop' fixture "
+        "or be used in tests depending from it."
+    )
+
+
+@pytest.mark.skipif(sys.version_info < (3, 6), reason='old python')
+def test_aiohttp_plugin_async_gen_fixture(testdir):
+    testdir.makepyfile("""\
+import asyncio
+import pytest
+from unittest import mock
+
+from aiohttp import web
+
+
+pytest_plugins = 'aiohttp.pytest_plugin'
+
+canary = mock.Mock()
+
+
+async def hello(request):
+    return web.Response(body=b'Hello, world')
+
+
+def create_app(loop):
+    app = web.Application()
+    app.router.add_route('GET', '/', hello)
+    return app
+
+
+@pytest.fixture
+async def cli(test_client):
+    yield await test_client(create_app)
+    canary()
+
+
+async def test_hello(cli):
+    resp = await cli.get('/')
+    assert resp.status == 200
+
+
+def test_finalized():
+    assert canary.called is True
+""")
+    nb_loops = len(LOOP_FACTORIES)
+    result = testdir.runpytest('-p', 'no:sugar')
+    result.assert_outcomes(passed=1 * nb_loops + 1)