'Test filtering results from each predicate type.'

def test_call(self):

    e = dict(obj=object())
    def callWithPredicateResult(result):
        seen = []
        observer = FilteringLogObserver((lambda e: seen.append(e)), ((lambda e: result),))
        observer(e)
        return seen
    self.assertIn(e, callWithPredicateResult(PredicateResult.yes))
    self.assertIn(e, callWithPredicateResult(PredicateResult.maybe))
    self.assertNotIn(e, callWithPredicateResult(PredicateResult.no))
