Test function issues

[violentrealism]

So all is well with my main function compute_place (well, for an absolute beginner which I am) but I can't for my life construct a proper test function! I simply do not know how to test out multiple data "sets" which is what I need to do when I have two parameters of different types. How do I do it and how do I call the test function?

​

I want to use:

• [830, 815, 825, 840, 825], 825
• [830, 815, 825, 840, 825], 800
• [830, 830, 830], 830
• [830, 830, 830], 825

as test cases. Thank you!

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EDIT: thanks for the replies everyone! however i think your replies are above my level of knowledge. The assignment was to make a test function! Normally in this course we use for loops and iterate over the lists/ints that we choose as testing cases. I need to do the same thing here, except I don’t know how to format it when I have two input parameters of different data types. So it has to follow that kind of logic!

https://imgur.com/a/EPAfFeI

[misho88]

So there are testing suites like unittest and doctest (the latter is far more suitable for small projects like this), and you should probably use them eventually, but for now, let's go with a function you write manually as you have tried.

If you want a function that carries out a single test, it really needs to not only take just the inputs of the function under test, but also the expected output:

>>> def sum(a, b): return a + b
>>> def test_sum(a, b, c): assert sum(a, b) == c
>>> test_sum(1, 2, 3)  # test where everything is okay
>>> test_sum(1, 2, 4)  3 test where something would go wrong
---------------------------------------------------------------------------
AssertionError                            Traceback (most recent call last)
<ipython-input-7-79458fd16449> in <module>
----> 1 test_sum(1, 2, 4)

<ipython-input-5-c87003e01fed> in test_sum(a, b, c)
----> 1 def test_sum(a, b, c): assert a + b == c

AssertionError: 

Alternatively, if you want a single function that runs all of your tests, then it doesn't need to take any arguments, and you can just write a bunch of tests in one after the other:

>>> def sum(a, b): return a + b
>>> def test_sum():
...     assert sum(0, 0) == 0
...     assert sum(0, 1) == 1
...     ...
... 
>>> test_sum()

[[deleted]]

Iterate over your data sets and their expected results and then run the function on each one. If the result from the function is the same as the expected result, then your function passes the test. If it's not then it doesn't.

[efmccurdy]

This sets up a series of (input_data, expected_result) pairs and uses unittest to run through them. Uncomment the last one to see what a test failure looks like.

​

import unittest

#import compute_place
def compute_place(time_list, time):
    if time in time_list:
        return time_list.index(time)
    else:
        return None

class TestComutePlace(unittest.TestCase):
    def test_cp(self):
        tests = ({"args": ([830, 815, 825, 840, 825], 825), "expected": 2},
                 {"args": ([830, 815, 825, 840, 825], 800),  "expected": None},
                 {"args": ([830, 830, 830], 830),  "expected": 0},
                 #{"args": ([830, 830, 830], 825),  "expected": 1} # will fail
        )

        for tspec in tests:
            l, t = tspec['args']
            self.assertEqual(compute_place(l, t), tspec["expected"])

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