My assertion fails for this piece of code in python

Question

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

p.s:- I am a beginner in python and unable to find out whats wrong. My assertion fails when I run the code.

Answer 1

False == 'c' in 'apple' is not interpreted as

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

but,

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

becaue of comparison chaining.

---

To get what you want, put parentheses explicitly.

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

or more preferably use in / not in:

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