Why don't pytest fixtures work as intended?

Question

I'm trying to use PyTest and I cannot obtain how to set fixtures. I've tried the following code:

import pytest
import random

@pytest.fixture()
def setup():
    a = random.randint(0, 10)

def test(setup):
    assert 3 > a
if __name__ == '__main__':
    pytest.main()

And I am getting "NameError: name 'a' is not defined".

Also the example from the official documentation doesn't work. What's wrong? I need functionality similar to setUp/tearDown . But I don't want to use unittest . Can someone provide me an example with working fixtures (both setUp type and tearDown type)?

I want to write some test as functions and some test as methods inside classes. Therefore me second question is for an working example of using fixture with classes/methods. I just need to see working examples of fixtures in Python.

Is there a different Python 3 unit testing framework with assertions as simple as in PyTest ?

Answer 1

Fixtures don't work like this. They cannot magically transfer the name a from one function's ( setup ) local scope to another's ( test ). Instead, your setup function must explicitly return the object that will be passed as the setup argument to your test function. For example:

import pytest
import random

class TestSetup:
    def __init__(self):
        self.a = random.randint(0, 10)

@pytest.fixture()
def setup():
    return TestSetup()

def test(setup):
    assert 0 <= setup.a <= 10

if __name__ == '__main__':
    pytest.main()

Answer 2

More typically you'd do something like:

/usr/bin/env python
import pytest
import random

@pytest.fixture()
def my_rand_int():
    return random.randint(0,10)

def test(my_rand_int):
    assert 3 > my_rand_int

if __name__ == '__main__':
    pytest.main()