'When given a callable that returns a failing Deferred, include the
failure the results list, tagged with a FAILURE flag.'

def test_singleAsynchronousFailure(self):

    d = util._runSequentially([(lambda : defer.fail(ValueError('foo')))])
    def check(results):
        [(flag, fail)] = results
        fail.trap(ValueError)
        self.assertEqual(fail.getErrorMessage(), 'foo')
        self.assertEqual(flag, defer.FAILURE)
    self.assertDeferredResult(d, check)
