def test_persistence_and_response_on_empty_words():
formula_1 = LTLfAlways(LTLfEventually(LTLfAtomic("a")))
formula_2 = LTLfEventually(LTLfAlways(LTLfAtomic("a")))
recurrence_truth = formula_1.truth([], 0)
persistence_truth = formula_2.truth([], 0)
assert recurrence_truth
assert not persistence_truth
def test_persistence_is_equivalent_to_response_on_nonempty_words(word):
formula_1 = LTLfAlways(LTLfEventually(LTLfAtomic("a")))
formula_2 = LTLfEventually(LTLfAlways(LTLfAtomic("a")))
assert formula_1.truth(word, 0) == formula_2.truth(word, 0)