asserts

Python Asserts

Stand-alone Assertions for Python

This package provides a few advantages over the assertions provided by unittest.TestCase:

• Can be used stand-alone, for example:
  • In test cases, not derived from TestCase.
  • In fake and mock classes.
  • In implementations as rich alternative to the assert statement.
• PEP 8 compliance.
• Custom stand-alone assertions can be written easily.
• Arguably a better separation of concerns, since TestCase is responsible for test running only, if assertion functions are used exclusively.

There are a few regressions compared to assertions from TestCase:

• The default assertion class (AssertionError) can not be overwritten. This is rarely a problem in practice.
• asserts does not support the addTypeEqualityFunc() functionality.

Usage:

>>> from asserts import assert_true, assert_equal, assert_raises
>>> my_var = 13
>>> assert_equal(13, my_var)
>>> assert_true(True, msg="custom failure message")
>>> with assert_raises(KeyError):
...     raise KeyError()

Failure messages can be customized:

>>> assert_equal(13, 14, msg_fmt="{got} is wrong, expected {expected}")
Traceback (most recent call last):
  ...
AssertionError: 14 is wrong, expected 13