Test::More : I'd need a "not

wazoox has asked for the wisdom of the Perl Monks concerning the following question:

Dear Monks,

I've decided to write proper test scripts for the modules I'm developing. I've checked Test::Simple and Test::More, and they're missing a feature that seems important for me : not_ok() function. I need to test that my subs work OK, but it's perhaps at least as important to check that they fail properly when feeded with bad data!
Test::More allows failed tests in a TODO: block, but that's not what I'm looking for. Does any of you know how I may solve this elegantly?

# this one should work
ok( my_sub('needs', 3, 'parameters'), "that's good!");

# this one should fail
not_ok(my_sub('bad parameter count'), "that fails!");
[download]

Comment on Test::More : I'd need a "not_ok()" function... Select or Download Code

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Re: Test::More : I'd need a "not_ok()" function... by castaway (Parson) on Oct 14, 2005 at 15:21 UTC
Sounds like you want dies_ok. C.	[reply]
Re^2: Test::More : I'd need a "not_ok()" function... by wazoox (Prior) on Oct 14, 2005 at 15:36 UTC
You saved my life :) All possible perl programs are already written, but you'll have to find out where first :)	[reply]
Re: Test::More : I'd need a "not_ok()" function... by inman (Curate) on Oct 14, 2005 at 14:41 UTC
Just negate the test. 'ok' is looking for the test to succeed. If you are testing a sub and are looking for it to fail then re-write the test such that the failure of the sub is a succesful test. `# this one should succeed when the sub fails ok(!my_sub('bad parameter count'), "Bad param test");` [download]	[reply] [d/l]
Re: Test::More : I'd need a "not_ok()" function... by philcrow (Priest) on Oct 14, 2005 at 14:48 UTC
Using a negated test works great, if your sub returns false for the error. Lately, Damian has been urging us to die when things go wrong. If my_sub follows that advice, then you need more than a negated test. You need an eval like this: `eval { my_sub( 'bad param count' ); }; is( $@, 'your error message', 'test name' );` [download] Which supports the OP's point that a not_ok might be in order, but only to test for a correct death message.	[reply] [d/l]
Re^2: Test::More : I'd need a "not_ok()" function... by wazoox (Prior) on Oct 14, 2005 at 15:05 UTC
That's exactly what's happening to me! `my_sub('bad')` actually dies, that's my problem... a `not_ok()` would allow less cluttered test scripts than `eval {...}; is($@, 'something', 'test');` I dare trying using a good ol' ugly prototype : `sub not_ok(&$) { my $coderef = shift; my $message = shift; eval $coderef; ok( $@, $message) } # call this way not_ok( sub { mysub('bad data') }, 'message')` [download] How do you find this? Not refined, but works.	[reply] [d/l] [select]
Re^3: Test::More : I'd need a "not_ok()" function... by Perl Mouse (Chaplain) on Oct 14, 2005 at 15:25 UTC
I wouldn't call it 'not_ok', as that suggests 'ok !'. You want to test it dying, so I'd call it something like: 'die_cmp' (for exact testing of the die message) or 'die_like' (for regex testing of the die message). `Perl --((8:>*`	[reply]
Re^3: Test::More : I'd need a "not_ok()" function... by philcrow (Priest) on Oct 14, 2005 at 16:01 UTC
I'm no expert on the internals of Test::More, but your method looks fine to me. I would follow the previous suggestion and call it die_ok or something similar. The maintainers usually have good opinions about the names. Phil	[reply]
Re^3: Test::More : I'd need a "not_ok()" function... by bluto (Curate) on Oct 14, 2005 at 16:12 UTC
The main problem with this is that the routine you are testing must die. You can't use it for tests that just return 0 for failure (i.e. the opposite of what "ok()" does). Perhaps it should be named something like "should_die"? Also, you may want to use 'like()' instead of 'ok()' if you are matching a die message that contains dynamic information (e.g. filename, line number, stack trace, etc).	[reply]