[Tutor] How to write tests for main() function that does not return anything

[Pedro Miguel]

Hi guys, I'm trying to test the code in the main() but I'm a bit unsure how to go about it since I'm not passing any arguments or even returning anything other then logging. For the purposes of the example I've shortened the tree statements in the function..
Can anyone point me in the right direction on how to test the logic below? Or perhaps give me an example on how to test the code below (that would be really appreciated). 
I've posted this question on Stackoverflow but the guys over there told me to mock it but no one provided an example (I'm fairly new on mocking)..and how could I mock the if statements or even the for loop?
script.py

from . import settings


def main():
    if settings.PATHS:  # list containing full paths to a directory of files
        paths = settings.PATHS
        for path in paths:
            data = read_file(path)
            modified_data = do_something_with_the_data_collected(data)
            write_to_new_file(modified_data)
    else:
        logger.warning("There are no files in {}".format(settings.FILES_DIRECTORY))

if __name__ == '__main__':
    main()
tests/file_tests.py
import unittest

from module.script import main


class FileManagerTests(unittest.TestCase):

    def test_main_func(self):
        main()  # ?? this is where I am stuck, should I just test 
                # that it logs correctly if certain data exists 
                # in settings file?

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

RegardsPedro+44(0)7549646235pedro.miguel at live.co.uk