doctest_mode

%doctest_mode:
    Toggle doctest mode on and off.

You can change the way that IPython’s prompts, exceptions, and output looks by running %doctest_mode. This makes it easy to copy and paste code that has characters such as >>> and ... and have it recognize it. This is also handy if you use doctests in your docstrings, as you can directly copy and paste them from the shell without having to leave the session and they are ready to use in your functions.

An example:

In [1]: def my_amazing_function(a, b):
    ...:     return a * b
    ...:

In [2]: %doctest_mode
Exception reporting mode: Plain
Doctest mode is: ON
>>> my_amazing_function(2, 4)
8
>>> my_amazing_function('woo', 3)
'woowoowoo'
>>> %doctest_mode
Exception reporting mode: Context
Doctest mode is: OFF

Now you can copy and paste the examples directly into your code’s docstring. Below is a complete working example, let’s say saved as example.py:

def my_amazing_function(a, b):
    """
    >>> my_amazing_function(2, 4)
    8
    >>> my_amazing_function('woo', 3)
    'woowoowoo'
    """
    return a * b

if __name__ == "__main__":
    import doctest
    doctest.testmod()

So running python example.py will run the doctest and verify your statements are true. You won’t see any message (since it passes) but you can pass in the -v parameter for it to print a verbose log.

python example.py -v

Trying:
    my_amazing_function(2, 4)
Expecting:
    8
ok
Trying:
    my_amazing_function('woo', 3)
Expecting:
    'woowoowoo'
ok
1 items had no tests:
    __main__
1 items passed all tests:
   2 tests in __main__.my_amazing_function
2 tests in 2 items.
2 passed and 0 failed.
Test passed.