Every Perl module needs a test file
Test driven development is a must, that's why I think it is necessary to check that there is at least a test for every module specially if you can't know a priori how much will be populated a namespace, for example if you decide to have plugins .
So here it comes a very nice core module called Module::Pluggable ! For sure ti can help a lot !
Read a short explanation ( more code than words :) in
this article .