Lists

Assertion failures for lists also show only differing items by default:

____________________ test_get_starting_equiment _____________________

    def test_get_starting_equiment():
        expected = ['long sword', 'shield']
>       assert get_starting_equipment('warrior') == expected
E       AssertionError: assert ['long sword'...et', 'shield'] == ['long sword', 'shield']
E         At index 1 diff: 'warrior set' != 'shield'
E         Left contains more items, first extra item: 'shield'
E         Use -v to get the full diff

tests\test_assert_demo.py:71: AssertionError

Note that pytest shows which index differs, and also that the -v flag can be used to show the complete difference between the lists:

____________________ test_get_starting_equiment _____________________

    def test_get_starting_equiment():
        expected = ['long sword', 'shield']
>       assert get_starting_equipment('warrior') == expected
E       AssertionError: assert ['long sword'...et', 'shield'] == ['long sword', 'shield']
E         At index 1 diff: 'warrior set' != 'shield'
E         Left contains more items, first extra item: 'shield'
E         Full diff:
E         - ['long sword', 'warrior set', 'shield']
E         ?               ---------------
E         + ['long sword', 'shield']

tests\test_assert_demo.py:71: AssertionError

If the difference is too big, pytest is smart enough to show only a portion to avoid showing too much output, displaying a message like the following:

E         ...Full output truncated (100 lines hidden), use '-vv' to show