Devel::Cover - An Introduction

Braga, Portugal -- 1st September 2005

Paul Johnson

www.pjcj.net

What is Devel::Cover

• Testing is important
• But how do you know if you are doing it correctly?
• Code coverage can help
• Devel::Cover is the code coverage tool for Perl
• Let's look at how it is used

Preparation

• Devel::Cover is on CPAN
• Download and install it

Tools you will need

• A C compiler
• Perl 5.6.1 at least

Using Devel::Cover

• cover -test

Using Devel::Cover

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

A worked example

• Shell::Source
• Sources shell scripts into your Perl program
• It's mine
• Download from CPAN as usual
• No need to install it

Normal Test

$ make test
PERL_DL_NONLAZY=1 /usr/bin/perl "-MExtUtils::Command::MM" \
  "-e" "test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
t/bash....ok
t/csh.....ok
t/ksh.....ok
t/sh......ok
t/tcsh....ok
t/zsh.....ok
All tests successful.
Files=6, Tests=24,  1 wallclock secs ( 0.49 cusr +  0.09 csys =  0.58 CPU)

Normal Test

$ make test
PERL_DL_NONLAZY=1 /usr/bin/perl "-MExtUtils::Command::MM" \
  "-e" "test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
t/bash....ok
t/csh.....ok
t/ksh.....ok
t/sh......ok
t/tcsh....ok
t/zsh.....ok
All tests successful.
Files=6, Tests=24,  1 wallclock secs ( 0.49 cusr +  0.09 csys =  0.58 CPU)

Normal Test

$ make test
PERL_DL_NONLAZY=1 /usr/bin/perl "-MExtUtils::Command::MM" \
  "-e" "test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
t/bash....ok
t/csh.....ok
t/ksh.....ok
t/sh......ok
t/tcsh....ok
t/zsh.....ok
All tests successful.
Files=6, Tests=24,  1 wallclock secs ( 0.49 cusr +  0.09 csys =  0.58 CPU)

Coverage Run

$ cover -test
Deleting database /home/pjcj/g/perl/Shell-Source-0.01/cover_db
PERL_DL_NONLAZY=1 /usr/local/pkg/cover/c1/perl-5.8.7/bin/perl "-MExtUtils::Command::MM" \
  "-e" "test_harness(0, 'blib/lib', 'blib/arch')" t/*.t
t/bash....ok
t/csh.....ok
t/ksh.....ok
t/sh......ok
t/tcsh....ok
t/zsh.....ok
All tests successful.
Files=6, Tests=24, 17 wallclock secs (16.16 cusr +  1.01 csys = 17.17 CPU)
Reading database from /home/pjcj/g/perl/Shell-Source-0.01/cover_db


---------------------------- ------ ------ ------ ------ ------ ------ ------
File                           stmt   bran   cond    sub    pod   time  total
---------------------------- ------ ------ ------ ------ ------ ------ ------
blib/lib/Shell/Source.pm       96.6   65.0   66.7   90.9    n/a  100.0   86.1
Total                          96.6   65.0   66.7   90.9    n/a  100.0   86.1
---------------------------- ------ ------ ------ ------ ------ ------ ------


Writing HTML output to /home/pjcj/g/perl/Shell-Source-0.01/cover_db/coverage.html ...
done.

Coverage Results

• Reminds us which database we are using
• Table showing each file
• Percentage of coverage achieved
• Fliename is a link

File Coverage

• Start with subroutine coverage

Subroutine Coverage

• Start with subroutine coverage
• ten of eleven subroutines run
• all run six times except for env
• BEGIN comes from
• use Module LIST
• which translates to
• BEGIN { require Module; import Module LIST }
• pod n/a => not documented

Statement Coverage

• 56 of 58 statements executed
• those in env uncovered
• testing env will bring 100% subroutine coverage and 100% subroutine coverage
• Start with subroutine coverage

Output