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