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Devel::Cover(3)	      User Contributed Perl Documentation      Devel::Cover(3)

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
       <http://lists.perl.org/list/perl-qa.html>.

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

REQUIREMENTS
       ·   Perl 5.6.1 or greater.  Perl 5.8.8 or greater is recommended.

	   Perl 5.7.0 is unsupported.  Perl 5.8.8 or greater is recommended.
	   Perl 5.8.7 has problems and may crash.  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.

OPTIONS
	-blib		    - "use blib" and ignore files matching \bt/ (default true
			      iff blib directory exists).
	-coverage criterion - Turn on coverage for the specified criterion.  Criteria
			      include statement, branch, condition, path, subroutine,
			      pod, time, all and none (default all available).
	-db cover_db	    - Store results in coverage db (default ./cover_db).
	-dir path	    - Directory in which coverage will be collected (default
			      cwd).
	-ignore RE	    - Set REs of files to ignore (default "/Devel/Cover\b").
	+ignore RE	    - Append to REs of files to ignore.
	-inc path	    - Set prefixes of files to ignore (default @INC).
	+inc path	    - Append to prefixes of files to ignore.
	-merge val	    - Merge databases, for multiple test benches (default on).
	-select RE	    - Set REs of files to select (default none).
	+select RE	    - Append to REs of files to select.
	-silent val	    - Don't print informational messages (default off).
	-subs_only val	    - Only cover code in subroutine bodies (default off).
	-replace_ops val    - Use op replacing rather than runops (default on).
	-summary val	    - Print summary information iff val is true (default on).

   More on Coverage Options
       You can specify options to some coverage criteria.  At the moment only
       pod coverage takes any options.	These are the parameters which are
       passed into the Pod::Coverage constructor.  The extra options are
       separated by dashes, and you may specify as many as you wish.  For
       example, to specify that all subroutines containing xx are private,
       call Devel::Cover with the option -coverage,pod-also_private-xx.

SELECTING FILES TO COVER
       You may select which files you want covered using the select, ignore
       and inc options.	 The system works as follows:

       Any file matching a RE given as a select option is selected.

       Otherwise, any file matching a RE given as an ignore option is ignored.

       Otherwise, any file in one of the inc directories is ignored.

       Otherwise the file is selected.

       You may add to the REs to select by using +select, or you may reset the
       selections using -select.  The same principle applies to the REs to
       ignore.

       The inc directories are initially populated with the contents of the
       @INC array at the time Devel::Cover was built.  You may reset these
       directories using -inc, or add to them using +inc.

       Although these options take regular expressions, you should not enclose
       the RE within // or any other quoting characters.

ENVIRONMENT
       The -silent option is turned on when Devel::Cover is invoked via
       $HARNESS_PERL_SWITCHES or $PERL5OPT.  Devel::Cover tries to do the
       right thing when $MOD_PERL is set.  $DEVEL_COVER_OPTIONS is appended to
       any options passed into Devel::Cover.

       When running Devel::Cover's own test suite, $DEVEL_COVER_DEBUG turns on
       debugging information, $DEVEL_COVER_GOLDEN_VERSION overrides
       Devel::Cover's own idea of which golden results it should test against,
       and $DEVEL_COVER_NO_COVERAGE runs the tests without collecting
       coverage.

ACKNOWLEDGEMENTS
       Some code and ideas cribbed from:

	Devel::OpProf
	B::Concise
	B::Deparse

SEE ALSO
	Devel::Cover::Tutorial
	B
	Pod::Coverage

LIMITATIONS
       There are things that Devel::Cover can't cover.

   Absence of shared dependencies
       Perl keeps track of which modules have been loaded (to avoid reloading
       them).  Because of this, it isn't possible to get coverage for a path
       where a runtime import fails if the module being imported is one that
       Devel::Cover uses internally.  For example, suppose your program has
       this function:

	sub foo {
	    eval { require Storable };
	    if ($@) {
		carp "Can't find Storable";
		return;
	    }
	    # ...
	}

       You might write a test for the failure mode as

	BEGIN { @INC = () }
	foo();
	# check for error message

       Because Devel::Cover uses Storable internally, the import will succeed
       (and the test will fail) under a coverage run.

       Modules used by Devel::Cover while gathering coverage:

       ·   B

       ·   B::Debug

       ·   B::Deparse

       ·   Carp

       ·   Cwd

       ·   Digest::MD5

       ·   File::Path

       ·   File::Spec

       ·   Storable

   mod_perl
       By adding "use Devel::Cover;" to your mod_perl startup script, you
       should be able to collect coverage information when running under
       mod_perl.  You can also add any options you need at this point.	I
       would suggest adding this as early as possible in your startup script
       in order to collect as much coverage information as possible.

   Redefined subroutines
       If you redefine a subroutine you may find that the original subroutine
       is not reported on.  This is because I haven't yet found a way to
       locate the original CV.	Hints, tips or patches to resolve this will be
       gladly accepted.

BUGS
       Almost certainly.

       See the BUGS file.  And the TODO file.

VERSION
       Version 0.78 - 17th May 2011

LICENCE
       Copyright 2001-2011, Paul Johnson (pjcj@cpan.org)

       This software is free.  It is licensed under the same terms as Perl
       itself.

       The latest version of this software should be available from my
       homepage: http://www.pjcj.net

perl v5.14.2			  2011-05-17		       Devel::Cover(3)
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