Tuesday, March 24, 2009

unittest - now with test skipping (finally)

Yesterday, I was happy to commit a patch which added test skipping and expected failure support to the venerable unittest module. It adds a skip() method to TestCase, which marks the current test being run as skipped, as well as a set of useful decorators. Here's a short example:

import sys
import unittest

class SkippingExample(unittest.TestCase):

@unittest.skip("testing skipping")
def test_skip_me(self):
self.fail("shouldn't happen")

def test_normal(self):
self.assertEqual(1, 1)

@unittest.skipIf(sys.version_info < (2, 6),
"not supported in this veresion")
def test_show_skip_if(self):
# testing some things here

def test_expected_failure(self):
self.fail("this should happen unfortunately")

# Yes, you can skip whole classes, too!
@unittest.skip("classing skipping")
class CompletelySkippedTest(unittest.TestCase):

def test_not_run_at_all(self):
self.fail("shouldn't happen")

if __name__ == "__main__":

Running it in verbose mode gives:

__main__.CompletelySkippedTest ... skipped 'classing skipping'
test_expected_failure (__main__.SkippingExample) ... expected failure
test_normal (__main__.SkippingExample) ... ok
test_show_skip_if (__main__.SkippingExample) ... ok
test_skip_me (__main__.SkippingExample) ... skipped 'testing skipping'

Ran 5 tests in 0.010s

OK (skipped=2, expected failures=1)

I have high hopes for this and Python's regression tests. Hopefully it will simplify the ugly system of test skipping we have now. It should also help us pacify other implementations who want CPython implementation detail tests skipped.