Devel::Cover package contains code coverage metrics for Perl.

SYNOPSIS

perl -MDevel::Cover yourprog args
cover

perl -MDevel::Cover=-db,cover_db,-coverage,statement,time yourprog args
To test an uninstalled module:
cover -delete
HARNESS_PERL_SWITCHES=-MDevel::Cover make test
cover
To test an uninstalled module which uses Module::Build (0.26 or later):
./Build testcover
If the module does not use the t/*.t framework:
PERL5OPT=-MDevel::Cover make test

This module provides code coverage metrics for Perl. Code coverage metrics describe how throroughly tests exercise code. By using Devel::Cover you can find areas of code not exercised by your tests and find out which tests to create to increase coverage. Code coverage can be considered as an indirect measure of quality.

If you cant guess by the version number this is an alpha release.
Code coverage data are collected using a pluggable runops function which counts how many times each op is executed. These data are then mapped back to reality using the B compiler modules. There is also a statement profiling facility which needs a better backend to be really useful.

The cover program can be used to generate coverage reports.

Statement, branch, condition, subroutine, pod and time coverage information is reported. Statement coverage data should be reasonable, although there may be some statements which are not reported. Branch and condition coverage data should be mostly accurate too, although not always what one might initially expect. Subroutine coverage should be as accurate as statement coverage. Pod coverage comes from Pod::Coverage. If Pod::Coverage::CountParents is available it will be used instead. Coverage data for path coverage are not yet collected.

The gcov2perl program can be used to convert gcov files to Devel::Cover databases.

You may find that the results dont match your expectations. I would imagine that at least one of them is wrong.

The most appropriate mailing list on which to discuss this module would be perl-qa. Discussion has migrated there from perl-qa-metrics which is now defunct. See http://lists.perl.org/showlist.cgi?name=perl-qa.