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Re^2: Toggling test plans with vim

by Ovid (Cardinal)
on Aug 09, 2006 at 11:11 UTC ( #566379=note: print w/replies, xml ) Need Help??

in reply to Re: Toggling test plans with vim
in thread Toggling test plans with vim

It can protect you when your tests end unexpectedly. For example, let's say you're running 30 tests. At some point, another programmer on your team writes a bad function which calls exit. Your tests might end prematurely and having a test plan catches that. Or maybe you've just updated a CPAN module which calls exit when it shouldn't or finds some other way of terminating your tests early. Again, having a test count will protect you. It's quite possible that a test can terminate early without any tests failing.

Another example is when someone does something like this (assumes Scalar::Util::looks_like_number() has been imported):

foreach my $num ( $point->coordinates ) { ok looks_like_number($num), "... and $num should be a number"; }

If that returns a different number of coordinates from what you expect, having a test plan will catch that. Admittedly, this should actually look something like this:

ok my @coordinates = $point->coordinates, 'coordinates() should return the coordinates'; is scalar @coordinates, 3, '... and it should return the correct numbe +r of them'; foreach my $num ( @coordinates ) { ok looks_like_number($num), "... and each should be a number ($num +)"; }

With that, because you're explicitly counting the number of coordinates, the test plan is not as necessary. However, as with the exit example, a test plan not only helps out when the code is less than perfect, it also helps out when the tests are less than perfect. It's such a small thing to update and when it actually catches a problem, you'll be greatful.

Some people argue, "yeah, but I never write code that stupid so this doesn't apply to me!". That's fine. If updating the test plan is too much work for them, so be it. Me, I know I make mistakes and I expect others to make mistakes. If we didn't make mistakes, we wouldn't need the tests in the first place.

(Trivia quiz: if the above tests were in a CPAN module, how might those tests fail?)


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Re^3: Toggling test plans with vim
by gam3 (Curate) on Aug 09, 2006 at 20:12 UTC
    Wouldn't having a tests_complete() function at the end of the test also solve (most of) these problems.
    -- gam3
    A picture is worth a thousand words, but takes 200K.
      That seems like a good idea to me. Why wouldn't this be a reasonable alternative to keeping track of a test count:
      use Test::More 'declare_done'; # tests here.... done_testing();
      I've declared that my plan is to declare when I'm done testing. At the end of the test script, I do just that. Now, if the script exits early and done_testing() hasn't be called, we know there was a problem, and we know where it is, because we know the last test that was run.
        Yeah. That's certainly a lot simpler than counting.

        I wish someone would write that module.

        Excellent idea. Simplicity incarnate.

        Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
        Lingua non convalesco, consenesco et abolesco. -- Rule 1 has a caveat! -- Who broke the cabal?
        "Science is about questioning the status quo. Questioning authority".
        In the absence of evidence, opinion is indistinguishable from prejudice.
      Maybe you should suggest it to the maintainer(s) of Test::More?
Re^3: Toggling test plans with vim
by diotalevi (Canon) on Aug 09, 2006 at 13:47 UTC

    I've never been caught out by an errant exit() but rather some kind of fault from bad XS. It looks like the script just exited but in reality something really horrible just occurred.

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