21.2 The assert statement

>>> import assert_test
>>> assert_test.example(0)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "assert_test.py", line 2, in example
    assert param > 0
AssertionError
>>>

21.2.1 Python's __debug__ variable

if __debug__:
    if not param > 0:
        raise AssertionError

>>> __debug__
True
>>> __debug__ = False
  File "<stdin>", line 1
SyntaxError: assignment to keyword

21.3 Tests in docstrings: doctests
 
>>> from typedlist import TypedList
>>> a_typed_list = TypedList(1, [1, 2, 3])
>>> a_typed_list[1] == 2
True
>>> a_typed_list[1] = 3
>>> a_typed_list[1]
3

21.3.1 Avoiding doctest traps

>>> my_dict = {'one': 1, 'two': 2}
>>> my_dict
{'one': 1, 'two': 2}

>>> my_dict == {'one': 1, 'two': 2}
True
>>> my_dict == {'two': 2, 'one': 1}
True