Pass a fixture to a helper function in PyTest?

问题

I have a function that needs to utilize a fixture in my test suite. This is just a small helper function that helps to generate a full URL.

def gen_url(endpoint):
    return "{}/{}".format(api_url, endpoint)

I have a fixture in conftest.py that returns the URL:

@pytest.fixture(params=["http://www.example.com"])
def api_url(request):
    return request.param

@pytest.fixture(params=["MySecretKey"])
def api_key(request):
    return request.param

Finally, in my test function, I need to call my gen_url:

def test_call_action_url(key_key):
    url = gen_url("player")
    # url should equal: 'http://www.example.com/player'
    # Do rest of test here...

When I do this, though, it throws an error saying that api_url isn't defined when gen_url is called. If I add api_url as a second parameter, I need to pass it as a second parameter. That's...not what I want to do.

Can I add api_url as a second parameter to gen_url without being required to pass it from the tests? Why can't I use it like api_key in my test_* function?

回答1:

If you make gen_url a fixture, it can request api_url without explicitly passing it:

@pytest.fixture
def gen_url(api_url):
    def gen_url(endpoint):
        return '{}/{}'.format(api_url, endpoint)
    return gen_url


def test_call_action_url(api_key, gen_url):
    url = gen_url('player')
    # ...

Additionally, if api_key is only used to make requests, a TestClient class could encapsulate it, so test methods would only require the client:

try:
    from urllib.parse import urljoin  # Python 3
except ImportError:
    from urlparse import urljoin  # Python 2

import requests

@pytest.fixture
def client(api_url, api_key):
    class TestClient(requests.Session):
        def request(self, method, url, *args, **kwargs):
            url = urljoin(api_url, api_key)
            return super(TestClient, self).request(method, url, *args, **kwargs)

    # Presuming API key is passed as Authorization header
    return TestClient(headers={'Authorization': api_key})


def test_call_action_url(client):
    response = client.get('player')  # requests <api_url>/player
    # ...

回答2:

multiple problems with your code, the fixture is not visible in your test code untill and unless you use it as your test parameter, you are not passing both the fixtures (api_url and api_key) to your test function and subsequently to your helper function. Here is the modified code (untested)

def gen_url(api_url, endpoint):
   return "{}/{}".format(api_url, endpoint)

def test_call_action_url(api_url, api_key):
   url = gen_url(api_url, "player")
   # url should equal: 'http://www.example.com/player'
   # Do rest of test here with api_key here...

来源：https://stackoverflow.com/questions/45923876/pass-a-fixture-to-a-helper-function-in-pytest

标签

python

pytest