'C{_trimFrames} removes traces of C{_runCallbacks} when getting an error
in a callback returned by a C{TestCase} based test.'

def test_deferred(self):

    test = erroneous.TestAsynchronousFail('test_fail')
    frames = self.getErrorFrames(test)
    self.checkFrames(frames, [('_later', 'twisted/trial/test/erroneous')])
