Re: Unit Test of method calling system() - how?

On 5/10/10, Martin Hansen <[e-mail]> wrote:
> How can I unit test the two methods:
>
> print_usage_full_and_exit
>
> and
>
> print_usage_short_and_exit
>
> http://pastie.org/953804
>
> Possibly, I need to change the code into something more testable!
>
> Ideas most welcome!

I would extract a helper from both methods which does the bulk of the
work (the first 2 lines) but does not exit. Then test the helper and
don't bother testing the methods that call it.

You then have the problem that this print_wiki command is printing
something to stdout, which you want to test. Either capture stdout in
the test and verify it contains what you want, or use backticks
(`...`) instead of system in your helper method.

Since print_wiki might change its behavior, you might think about
making the assertion that tests print_wiki's output string somewhat
loose.... just verify that some expected substring occurs in there
somewhere, rather than verifying that it is exactly equal to some
expected string.

$0 is also going to present you some problems in a test... it will not
be the same value in the test as it is when run from your main
program. Not sure what to suggest about that without more context.

3 other points:

  looks like both methods have an unintended extra trailing + on their
first line

  standard style is to use 2 spaces for indentation; you appear to be using 8

  since the 2 methods are nearly identical, you should pull out the common code.