import py failure_demo = py.path.local(__file__).dirpath('failure_demo.py') pytest_plugins = 'pytester', def test_failure_demo_fails_properly(testdir): target = testdir.tmpdir.join(failure_demo.basename) failure_demo.copy(target) failure_demo.copy(testdir.tmpdir.join(failure_demo.basename)) result = testdir.runpytest(target, syspathinsert=True) result.stdout.fnmatch_lines([ "*42 failed*" ]) assert result.ret != 0