xfail 1.0.0

Skip expected failures and raise error if unexpectedly passed

XFail provides a decorator function xfail to skip expected exceptions. Similar to unittest.skipIf, but xfail can specify which exception should be skipped, and raise if unexpectedly passed (with strict=True argument).

Usage

xfail decorator

xfail accepts two arguments, the first argument exceptions and the second argument strict.

exceptions should be an Exception class to skip, like Exception, AssertionError, and so on. If you want to skip multiple exceptions, use tuple of them, for example, @xfail((AssertionError, ValueError)).

strict should be a boolean and by default it is False. If it was True and the decorated function did not raise expected error, XPassFailure exception would be raised.

from xfail import xfail

@xfail(IndexError)
def get(l, index):
    return l[index]

l = [1, 2, 3]
get(4)  # no error

Also supports multiple exceptions:

@xfail((IndexError, ValueError))
def a():
    '''This function passes IndexError and ValueError
    ...

In test script, similar to unittest.TestCase.assertRaises:

from unittest import TestCase
from xfail import xfail

class MyTest(TestCase):
    def test_1(self):
        @xfail(AssertionError)
        def should_raise_error():
            assert False
        a()  # test passes

    def test_2(self):
        @xfail(AssertionError, strict=True)
        def should_raise_error():
            assert True
        a()  # test failes, since this function should raise AssertionError

    # Can be used for test function
    @xfail(AssertionError, strict=True)
    def test_3(self)
        assert False

    # This test will fail
    @xfail(AssertionError, strict=True)
    def test_3(self)
        assert True

For more exapmles, see test_xfail.py.