examples/pytest/test_string_equal.py
def get_string():
    return "abc"

def test_string_equal():
    assert get_string() == "abd"

$ pytest test_string_equal.py

    def test_string_equal():
>       assert get_string() == "abd"
E       AssertionError: assert 'abc' == 'abd'
E         - abc
E         + abd