我的断言在python中的这段代码失败了

Question

def test_string_membership():
    assert False == 'c' in 'apple'
    assert True == 'a' in 'apple'
    assert True == 'app' in 'apple'

ps: - 我是python的初学者,无法找出错误.当我运行代码时,我的断言失败了.

Answer 1

False == 'c' in 'apple' 不解释为

False == ('c' in 'apple')

但,

(False == 'c') and ('c' in apple)

因为比较链.

为了得到你想要的东西,明确地加上括号.

False == ('c' in 'apple')

或更优选使用in/ not in:

def test_string_membership():
    assert 'c' not in 'apple'
    assert 'a' in 'apple'
    assert 'app' in 'apple'