Why is my unit test returning False instead of True?

Question

I'm running my first unit test on this function contained in a module called updater:

import logging
import subprocess

logger = logging.getLogger(__name__)

def update_oncourt():
    return_code = subprocess.run(['perl', 'oncourt_update.pl']).returncode
    if return_code == 0:
        logger.info('Updated OnCourt with latest data')
        return True
    else:
        logger.warning(f'OnCourt update errored with code: {return_code}')
        return False

I'm using the following unittest method:

from unittest import main, TestCase
from unittest.mock import patch

import updater

class TestStuff(TestCase):
    def test_update_oncourt(self):
        with patch('updater.subprocess.run') as mocked_run:
            mocked_run.return_value.returncode == 0
            return_code = updater.update_oncourt()
            mocked_run.assert_called_with(['perl', 'oncourt_update.pl'])
            self.assertTrue(return_code)


if __name__ == '__main__':
    main()

I realise this is very simplistic but I'm just trying to understand the basics at this stage.

I'm expecting return_code to be True and it's False:

self.assertTrue(return_code)
AssertionError: False is not true

Print out the return code and then try to understand why you're seeing that error. — cs95, Jul 16 '20 at 08:21
Adding `print('return_code', return_code)` you can see the problem: `return_code ` — jonrsharpe, Jul 16 '20 at 08:37
`mocked_run.return_value.returncode == 0` - that's an equality comparison, not an assignment — jonrsharpe, Jul 16 '20 at 08:49
It took me a while to spot it too - we read what we expect to read, not necessarily what's written! — jonrsharpe, Jul 16 '20 at 09:21

Why is my unit test returning False instead of True?

0 Answers0