Filter tests after discover

Question

I'm currently running my tests like this:

tests = unittest.TestLoader().discover('tests')
unittest.TextTestRunner().run(tests)

Now I want to run a specific test knowing his name (like test_valid_user) but not knowing his class. If there is more than one test with such name than I would like to run all such tests. Is there any way to filter tests after discover?

Or maybe there are other solutions to this problem (please note that it shouldn't be done from command line)?

Answer 1

You can use the unittest.loader.TestLoader.testMethodPrefix instance variable to change the test methods filter according to a different prefix than "test".

Say you have a tests directory with this king of unit tests:

import unittest


class MyTest(unittest.TestCase):
    def test_suite_1(self):
        self.assertFalse("test_suite_1")

    def test_suite_2(self):
        self.assertFalse("test_suite_2")

    def test_other(self):
        self.assertFalse("test_other")

You can write your own discover function to discover only test functions starting with "test_suite_", for instance:

import unittest


def run_suite():
    loader = unittest.TestLoader()
    loader.testMethodPrefix = "test_suite_"
    suite = loader.discover("tests")
    result = unittest.TestResult()
    suite.run(result)
    for test, info in result.failures:
        print(info)


if __name__ == '__main__':
    run_suite()

remark: the argument "tests" in the discover method is a directory path, so you may need to write a fullpath.

As a result, you'll get:

Traceback (most recent call last):
  File "/path/to/tests/test_my_module.py", line 8, in test_suite_1
    self.assertFalse("test_suite_1")
AssertionError: 'test_suite_1' is not false

Traceback (most recent call last):
  File "/path/to/tests/test_my_module.py", line 11, in test_suite_2
    self.assertFalse("test_suite_2")
AssertionError: 'test_suite_2' is not false

Answer 2

Another simpler way, would be to use py.test with the -k option which does a test name keyword scan. It will run any tests whose name matches the keyword expression.

Although that is using the command-line which you didn't want, please not that you can call the command-line from your code using subprocess.call to pass any arguments you want dynamically.

E.g.: Assuming you have the following tests:

def test_user_gets_saved(self): pass
def test_user_gets_deleted(self): pass
def test_user_can_cancel(self): pass

You can call py.test from cli:

$ py.test -k "test_user"

Or from code:

return_code = subprocess.call('py.test -k "test_user"', shell=True)