Code snippet to accompany blogpost on 5 pytest best practices

test_parametrize.py

import pytest


def divide(a, b):
    return a / b


@pytest.mark.parametrize("a, b, expected, is_error", [
    (1, 1, 1, False),
    (42, 1, 42, False),
    (84, 2, 42, False),
    (42, "b", TypeError, True),
    ("a", 42, TypeError, True),
    (42, 0, ZeroDivisionError, True),
])
def test_divide_antipattern(a, b, expected, is_error):
    if is_error:
        with pytest.raises(expected):
            divide(a, b)
    else:
        assert divide(a, b) == expected


@pytest.mark.parametrize("a, b, expected", [
    (1, 1, 1),
    (42, 1, 42),
    (84, 2, 42),
])
def test_divide_ok(a, b, expected):
    assert divide(a, b) == expected


@pytest.mark.parametrize("a, b, expected", [
    (42, "b", TypeError),
    ("a", 42, TypeError),
    (42, 0, ZeroDivisionError),
])
def test_divide_error(a, b, expected):
    with pytest.raises(expected):
        divide(a, b)