Python Testing with pytest

Failing with pytest.fail() and Exceptions

A test will fail if there is any uncaught exception. This can happen if

• an assert statement fails, which will raise an AssertionError exception,
• the test code calls pytest.fail(), which will raise an exception, or
• any other exception is raised.

While any exception can fail a test, I prefer to use assert. In rare cases where assert is not suitable, use pytest.fail().

Here’s an example of using pytest’s fail() function to explicitly fail a test:

ch2/test_alt_fail.py

import pytest
from cards import Card


def test_with_fail():
    c1 = Card("sit there", "brian")
    c2 = Card("do something", "okken")
    if c1 != c2:
        pytest.fail("they don't match")

Here’s what the output looks like: ...