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/showlist.cgi?name=perl-qa>.
The Devel::Cover repository can be found at
<http://github.com/pjcj/Devel--Cover>.
REQUIREMENTS
* Perl 5.6.1 or greater. Perl 5.8.2 or greater is recommended.
Perl 5.7.0 is unsupported. Perl 5.8.2 or greater is recommended.
Whilst Perl 5.6 should mostly work you will probably miss out on
coverage information which would be available using a more modern
version and will likely run into bugs in perl. Perl 5.8.0 will give
slightly different results to more recent versions due to changes in
the op tree.
* The ability to compile XS extensions.
This means a working compiler and make program at least.
* Storable and Digest::MD5
Both are in the core in Perl 5.8.0 and above.
* Template and PPI::HTML or Perl::Tidy
if you want syntax highlighted HTML reports.
* Pod::Coverage
if you want Pod coverage.
* Test::More
in order to run the tests
* Test::Warn
in order to run some of the tests
* Test::Differences
if the tests fail and you would like nice output telling you why.