@Patch decorator is not compatible with pytest fixture

Solution 1:

When using pytest fixture with mock.patch, test parameter order is crucial.

If you place a fixture parameter before a mocked one:

from unittest import mock

@mock.patch('my.module.my.class')
def test_my_code(my_fixture, mocked_class):

then the mock object will be in my_fixture and mocked_class will be search as a fixture:

fixture 'mocked_class' not found

But, if you reverse the order, placing the fixture parameter at the end:

from unittest import mock

@mock.patch('my.module.my.class')
def test_my_code(mocked_class, my_fixture):

then all will be fine.

Solution 2:

As of Python3.3, the mock module has been pulled into the unittest library. There is also a backport (for previous versions of Python) available as the standalone library mock.

Combining these 2 libraries within the same test-suite yields the above-mentioned error:

E       fixture 'fixture_name' not found

Within your test-suite's virtual environment, run pip uninstall mock, and make sure you aren't using the backported library alongside the core unittest library. When you re-run your tests after uninstalling, you would see ImportErrors if this were the case.

Replace all instances of this import with from unittest.mock import <stuff>.

Solution 3:

Hopefully this answer on an old question will help someone.

First off, the question doesn't include the error, so we don't really know what's up. But I'll try to provide something that helped me.

If you want a test decorated with a patched object, then in order for it to work with pytest you could just do this:

@mock.patch('mocked.module')
def test_me(*args):
    mocked_module = args[0]

Or for multiple patches:

@mock.patch('mocked.module1')
@mock.patch('mocked.module')
def test_me(*args):
    mocked_module1, mocked_module2 = args

pytest is looking for the names of the fixtures to look up in the test function/method. Providing the *args argument gives us a good workaround the lookup phase. So, to include a fixture with patches, you could do this:

# from question
@pytest.fixture(scope="module")
def brands():
    return 1

@mock.patch('mocked.module1')
def test_me(brands, *args):
    mocked_module1 = args[0]

This worked for me running python 3.6 and pytest 3.0.6.

Solution 4:

If you have multiple patches to be applied, order they are injected is important:

# from question
@pytest.fixture(scope="module")
def brands():
    return 1

# notice the order
@patch('my.module.my.class1')
@patch('my.module.my.class2')
def test_list_instance_elb_tg(mocked_class2, mocked_class1, brands):
    pass

Solution 5:

This doesn't address your question directly, but there is the pytest-mock plugin which allows you to write this instead:

def test_compute_scores(brands, mock):                 
     mock_b = mock.patch('test_test.b')
     a()