Perl Testing Patterns

Comprehensive testing strategies for Perl applications using Test2::V0, Test::More, prove, and TDD methodology.

When to Activate

• Writing new Perl code (follow TDD: red, green, refactor)
• Designing test suites for Perl modules or applications
• Reviewing Perl test coverage
• Setting up Perl testing infrastructure
• Migrating tests from Test::More to Test2::V0
• Debugging failing Perl tests

TDD Workflow

Always follow the RED-GREEN-REFACTOR cycle.

# Step 1: RED — Write a failing test
# t/unit/calculator.t
use v5.36;
use Test2::V0;

use lib 'lib';
use Calculator;

subtest 'addition' => sub {
    my $calc = Calculator->new;
    is($calc->add(2, 3), 5, 'adds two numbers');
    is($calc->add(-1, 1), 0, 'handles negatives');
};

done_testing;

# Step 2: GREEN — Write minimal implementation
# lib/Calculator.pm
package Calculator;
use v5.36;
use Moo;

sub add($self, $a, $b) {
    return $a + $b;
}

1;

# Step 3: REFACTOR — Improve while tests stay green
# Run: prove -lv t/unit/calculator.t

Test::More Fundamentals

The standard Perl testing module — widely used, ships with core.

Basic Assertions

use v5.36;
use Test::More;

#…