NAME

Devel::Cover - Code coverage metrics for Perl

SYNOPSIS

To get coverage for an uninstalled module:

cover -test

or 

     cover -delete
     HARNESS_PERL_SWITCHES=-MDevel::Cover make test
     cover

To get coverage for 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

If you want to get coverage for a program: 

     perl -MDevel::Cover yourprog args
     cover

     perl -MDevel::Cover=-db,cover_db,-coverage,statement,time yourprog args

DESCRIPTION

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

I consider this software to have an alpha status. By that I mean that I reserve the right to alter the interface in a backwards incompatible manner without incrementing the major version number. I specifically do not mean that this software is full of bugs or missing key features. Although I'm making no guarantees on that front either. In short, if you are looking for code coverage software for Perl, you have probably come to the end of your search. For more of my opinions on this subject, see http://pjcj.sytes.net/notes/2007/03/14#alpha

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. This release also includes an experimental mode which replaces ops instead of using a pluggable runops function. This provides a nice speed increase, but needs better testing before it becomes the default. You probably don't care about any of this.

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 don't 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/list/perl-qa.html>.

The Devel::Cover repository can be found at <http://github.com/pjcj/Devel--Cover>.

REQUIREMENTS