In February I wrote an arti­cle sur­vey­ing excep­tion han­dling in Perl, rec­om­mend­ing that devel­op­ers use Test::Exception to make sure their code behaves as expect­ed. A com­menter on Reddit sug­gest­ed I check out Test::Fatal as an alter­na­tive. What advan­tages does it hold over Test::Exception?

  • It only exports one func­tion com­pared to Test::Exception’s four: exception, which you can then use with the full suite of reg­u­lar Test::More func­tions as well as oth­er test­ing libraries such as Test::Deep.
  • It does­n’t over­ride the caller func­tion or use Sub::Uplevel to hide your test blocks from the call stack, so if your excep­tion returns a stack trace you’ll get out­put from the test as well as the thing throw­ing the excep­tion. The author con­sid­ers this a fea­ture since Sub::Uplevel is twitchy.”

To ease port­ing, Test::Fatal also includes two func­tions, dies_ok and lives_ok, replac­ing Test::Exception’s func­tions of the same names. dies_ok does not pro­vide the excep­tion thrown, though, so if you’re test­ing that you’ll need to use exception along with a TAP-emit­ting func­tion like is() or like().

And that’s it! Either is a valid choice; it comes down to whether you pre­fer one approach over anoth­er. Test::Exception is also includ­ed as part of Test::Mosts require­ments, so if you’re using the lat­ter to reduce boil­er­plate you’ll be get­ting the former.

Postscript:

I’d be remiss if I did­n’t also men­tion Test2::Tools::Exception, which is the pre­ferred way to test excep­tions using the Test2 frame­work. If you’re using Test2, ignore all the above and go straight to Test2::Tools::Exception.