Unittest tests order

How can I be sure of the unittest methods' order? Is the alphabetical or numeric prefixes the proper way?

class TestFoo(TestCase):
    def test_1(self):
        ...
    def test_2(self):
        ...

or

class TestFoo(TestCase):
    def test_a(self):
        ...
    def test_b(self):
        ...

Solution 1:

You can disable it by setting sortTestMethodsUsing to None:

import unittest
unittest.TestLoader.sortTestMethodsUsing = None

For pure unit tests, you folks are right; but for component tests and integration tests... I do not agree that you shall assume nothing about the state. What if you are testing the state?

For example, your test validates that a service is auto-started upon installation. If in your setup, you start the service, then do the assertion, and then you are no longer testing the state, but you are testing the "service start" functionality.

Another example is when your setup takes a long time or requires a lot of space and it just becomes impractical to run the setup frequently.

Many developers tend to use "unit test" frameworks for component testing...so stop and ask yourself, am I doing unit testing or component testing?

Solution 2:

There is no reason given that you can't build on what was done in a previous test or should rebuild it all from scratch for the next test. At least no reason is usually offered but instead people just confidently say "you shouldn't". That isn't helpful.

In general I am tired of reading too many answers here that say basically "you shouldn't do that" instead of giving any information on how to best do it if in the questioners judgment there is good reason to do so. If I wanted someone's opinion on whether I should do something then I would have asked for opinions on whether doing it is a good idea.

That out of the way, if you read say loadTestsFromTestCase and what it calls it ultimately scans for methods with some name pattern in whatever order they are encountered in the classes method dictionary, so basically in key order. It take this information and makes a testsuite of mapping it to the TestCase class. Giving it instead a list ordered as you would like is one way to do this. I am not so sure of the most efficient/cleanest way to do it but this does work.