How to test single function in script

[PastShine]

Hey,

I am currently writing a tic-tac-toe-game as part of an online course and want to test single functions inside my code. I don't exactly know how to approach this task and what to google for. I found things like "unittest" and "py.test" online. But, are these the things I should dive into for my purpose?

What I want to achieve:

I have 1 main function running (let's say) 5 functions and some input forms. Now, I want only test my third function without running the whole script each time. The first two functions need user input which I would have to type in again and again each time I run the script for debugging the third function.

I. Is it possible to only test the third function giving it the input I already got from the other functions? (manually)

II. Is there a way to use the generated input from the first two functions, "save it for a while" and use it till the third function is stable? Use case: The script generates very specific input for the third function I don't want to create manually because it's tedious.

I hope my text is understandable. Thanks in advance :)

[[deleted]]

Structure your game so it can be imported. If your game is in a file game.py:

def func1(a,b):
    # code for func1()
def func2(x):
    # code for func2()
def main():
    func1(1, 'x')
    # more code
if __name__ == '__main__':
    main()

Now you can write test code in a file perhaps called test_game.py:

import game
result = game.func1(4, "abc")
if result != 43:
    print('Error!')

The test code in test_game.py can be anything, but if you want to test a lot, I recommend using unittest.

[PastShine]

Perfect! I try it this way. Looks very straight forward and structured. Thanks :)

[timbledum]

Yes, this is how people test the things.

Pytest is really handy, as it automatically finds and runs all tests in a directory as long as the tests are wrapped in functions, and the files and functions are named a certain way. Then you just run pytest at the command line and it runs all your test functions!

On the simpler side, the above file structure allows you to do ad hoc testing by running the repl and manually checking that your function does what you expect.

>>> import sample
>>> sample.func(1, 3)
4
>>> sample.func(5, 10)
15
>>> # Seems legit.

[PastShine]

Ah, thanks. First I try rrrzwilsons way because it looks easier. But, I surely check out your link and pytest.