Question

Is there an existing plugin which could be used like:

@nose.plugins.expectedfailure
def not_done_yet():
    a = Thingamajig().fancynewthing()
    assert a == "example"

If the test fails, it would appear like a skipped test:

$ nosetests
...S..

..but if it unexpected passes, it would appear similarly to a failure, maybe like:

=================================
UNEXPECTED PASS: not_done_yet
---------------------------------
-- >> begin captured stdout << --
Things and etc
...

Kind of like SkipTest, but not implemented as an exception which prevents the test from running.

Only thing I can find is this ticket about supporting the unittest2 expectedFailure decorator (although I’d rather not use unittest2, even if nose supported it)

Answer 1

I don’t know about a nose plugin, but you could easily write your own decorator to do that. Here’s a simple implementation:

import functools
import nose

def expected_failure(test):
    @functools.wraps(test)
    def inner(*args, **kwargs):
        try:
            test(*args, **kwargs)
        except Exception:
            raise nose.SkipTest
        else:
            raise AssertionError('Failure expected')
    return inner

If I run these tests:

@expected_failure
def test_not_implemented():
    assert False

@expected_failure
def test_unexpected_success():
    assert True

I get the following output from nose:

tests.test.test_not_implemented ... SKIP
tests.test.test_unexpected_success ... FAIL

======================================================================
FAIL: tests.test.test_unexpected_success
----------------------------------------------------------------------
Traceback (most recent call last):
  File "C:\Python32\lib\site-packages\nose-1.1.2-py3.2.egg\nose\case.py", line 198, in runTest
    self.test(*self.arg)
  File "G:\Projects\Programming\dt-tools\new-sanbi\tests\test.py", line 16, in inner
    raise AssertionError('Failure expected')
AssertionError: Failure expected

----------------------------------------------------------------------
Ran 2 tests in 0.016s

FAILED (failures=1)