Perl Language Perl Unit Testing Example


The following is a simple example Perl test script, that gives some structure to allow for testing of other methods in the class/package under test. The script produces standard output with simple "ok" / "not ok" text, which is called TAP (Test Anything Protocol).

Typically the prove command runs the script(s) and summarises the test results.

#!/bin/env perl
use Modern::Perl;
use Carp;
use Test::More;
use Test::Exception;
use Const::Fast;

# Custom
BEGIN { use_ok('Local::MyPackage'); }

const my $PACKAGE_UNDER_TEST => 'Local::MyPackage';

# Example test of method 'file_type_build'
sub test_file_type_build {
    my %arg    = @_;
    my $label  = 'file_type_build';
    my $got_file_type;
    my $filename = '/etc/passwd';

    # Check the method call lives
        sub {
            $got_file_type = $PACKAGE_UNDER_TEST->file_type_build(
                filename => $filename
        "$label - lives"

    # Check the result of the method call matches our expected result.
    like( $got_file_type, qr{ASCII[ ]text}ix, "$label - result" );
} ## end sub test_file_type_build

# More tests can be added here for method 'file_type_build', or other methods.


   subtest 'file_type_build' => sub {
      # More tests of the method can be added here.

   # Tests of other methods can be added here, just like above.

} ## end MAIN:

Best Practice

A test script should only test one package/class, but there many scripts may be used to test a package/class.

Further Reading