I'm working on a project that involves building a prototype application in Perl. I've made extensive use of Perl's OO features and have a collection of classes that implement the mathematical calculations necessary to drive the web site running the application. Naturally, as I've been building the classes I've been building a unit test suite. Since Test::Class is the closest thing Perl has to junit or cppunit I'm using it to test all the class methods in my Perl classes. Everything was looking good until I told the guy writing the server to integrate with my code. His code died with an error like this: Can't locate object method "new" via package "Class::A" (perhaps you forgot to load "Class::A" at Class/B.pm line 147. Taking a quick look inside Class::B revealed that it did try to create a new Class::A object and that, sure enough, there was no use Class::A; anywhere in Class::B . Easy enough bug to fix, but w