Any way to pass parameters into pytest fixture?

Question

I am not talking about the Parameterizing a fixture feature that allows a fixture to be run multiple times for a hard-coded set of parameters.

I have a LOT of tests that follow a pattern like:

httpcode = 401  # this is different per call
message = 'some message'  # this is different per call
url = 'some url'  # this is different per call


mock_req = mock.MagicMock(spec_set=urllib2.Request)
with mock.patch('package.module.urllib2.urlopen', autospec=True) as mock_urlopen, \
     mock.patch('package.module.urllib2.Request', autospec=True) as mock_request:
    mock_request.return_value = mock_req
    mock_urlopen.side_effect = urllib2.HTTPError(url, httpcode, message, {}, None)
    connection = MyClass()
    with pytest.raises(MyException):
        connection.some_function()  # this changes

Essentially, I have a class that's an API client, and includes custom, meaningful exceptions that wrap urllib2 errors in something API-specific. So, I have this one pattern - patching some methods, and setting side effects on one of them. I use it in probably a dozen different tests, and the only differences are the three variables which are used in part of the side_effect, and the method of MyClass() that I call.

Is there any way to make this a pytest fixture and pass in these variables?

Answer 1

You can use indirect fixture parametrization http://pytest.org/latest/example/parametrize.html#deferring-the-setup-of-parametrized-resources

@pytest.fixture()
def your_fixture(request):
    httpcode, message, url = request.param
    mock_req = mock.MagicMock(spec_set=urllib2.Request)
    with mock.patch('package.module.urllib2.urlopen', autospec=True) as mock_urlopen, \
         mock.patch('package.module.urllib2.Request', autospec=True) as mock_request:
        mock_request.return_value = mock_req
        mock_urlopen.side_effect = urllib2.HTTPError(url, httpcode, message, {}, None)
        connection = MyClass()
        with pytest.raises(MyException):
            connection.some_function()  # this changes


@pytest.mark.parametrize('your_fixture', [
    (403, 'some message', 'some url')
], indirect=True)
def test(your_fixture):
   ...

and your_fixture will run before test with desired params