It might be nice if the doctest example set the appropriate exit status.  Apologies if this is beyond the scope of the example, but I thought it might be good practice.

Here is the file:
https://github.com/python/cpython/blob/master/Doc/library/doctest.rst

Here is the example as written:
if __name__ == "__main__":
    import doctest
    doctest.testmod()

Here is my proposal:
if __name__ == '__main__':
    import doctest
    import sys
    results = doctest.testmod()
    sys.exit(bool(results.failed))

I'm happy to fork the repo and submit a PR, if that makes things easier.  I'm not familiar with the protocol here.  Thanks for the great work!

Hi Rajiv, thanks for the report, but this is already possible by default. I will use the factorial example from https://docs.python.org/3.5/library/doctest.html to demonstrate it:

    $ python -m doctest example.py
    $ echo $?
    0

Now change the following line

    >>> [factorial(n) for n in range(6)]

to

    >>> [factorial(n) for n in range(5)]

and run the script again:

    $ python -m doctest example.py
    [...]
    ***Test Failed*** 1 failures.
    $ echo $?
    1

Rajiv is suggesting an improvement to the documentation.  I think it is a reasonable thought, but probably not a good idea on closer examination.  The example introduces the basic doctest concepts, and goes on to say that this is not the mostly likely way to make use of doctest (and indeed it is not common).  So complicating the example and the explanation would be counterproductive to the intent of the text, in my opinion.