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;

# Plan upfront or use done_testing
# plan tests => 5;  # Fixed plan (optional)

# Equality
is($result, 42, 'returns correct value');
isnt($result, 0, 'not zero');

# Boolean
ok($user->is_active, 'user is active');
ok(!$user->is_banned, 'user is not banned');

# Deep comparison
is_deeply(
    $got,
    { name => 'Alice', roles => ['admin'] },
    'returns expected structure'
);

# Pattern matching
like($error, qr/not found/i, 'error mentions not found');
unlike($output, qr/password/, 'output hides password');

# Type check
isa_ok($obj, 'MyApp::User');
can_ok($obj, 'save', 'delete');

done_testing;

SKIP and TODO

use v5.36;
use Test::More;

# Skip tests conditionally
SKIP: {
    skip 'No database configured', 2 unless $ENV{TEST_DB};

    my $db = connect_db();
    ok($db->ping, 'database is reachable');
    is($db->version, '15', 'correct PostgreSQL version');
}

# Mark expected failures
TODO: {
    local $TODO = 'Caching not yet implemented';
    is($cache->get('key'), 'value', 'cache returns value');
}

done_testing;

Test2::V0 Modern Framework

Test2::V0 is the modern replacement for Test::More — richer assertions, better diagnostics, and extensible.

Why Test2?

• Superior deep comparison with hash/array builders
• Better diagnostic output on failures
• Subtests with cleaner scoping
• Extensible via Test2::Tools::* plugins
• Backward-compatible with Test::More tests

Deep Comparison with Builders

use v5.36;
use Test2::V0;

# Hash builder — check partial structure
is(
    $user->to_hash,
    hash {
        field name  => 'Alice';
        field email => match(qr/\@example\.com$/);
        field age   => validator(sub { $_ >= 18 });
        # Ignore other fields
        etc();
    },
    'user has expected fields'
);

# Array builder
is(
    $result,
    array {
        item 'first';
        item match(qr/^second/);
        item DNE();  # Does Not Exist — verify no extra items
    },
    'result matches expected list'
);

# Bag — order-independent comparison
is(
    $tags,
    bag {
        item 'perl';
        item 'testing';
        item 'tdd';
    },
    'has all required tags regardless of order'
);

Subtests

use v5.36;
use Test2::V0;

subtest 'User creation' => sub {
    my $user = User->new(name => 'Alice', email => '[email protected]');
    ok($user, 'user object created');
    is($user->name, 'Alice', 'name is set');
    is($user->email, '[email protected]', 'email is set');
};

subtest 'User validation' => sub {
    my $warnings = warns {
        User->new(name => '', email => 'bad');
    };
    ok($warnings, 'warns on invalid data');
};

done_testing;

Exception Testing with Test2

use v5.36;
use Test2::V0;

# Test that code dies
like(
    dies { divide(10
how to use perl-testing
CursorClaude CodeClineCodexWindsurfGooseGitHub CopilotVS CodeGemini CLIKiloOpencodeKimi CLIRoo ClineAiderContinueZedBolt.newLovablev0Replit AgentSweepSmol DeveloperDevinCavemanAmpAntigravity
How to use perl-testing on Cursor
AI-first code editor with Composer
1
Prerequisites
Before installing skills in Cursor, ensure your development environment meets these requirements:
›Cursor installed and configured on your development machine
›Node.js version 16.0+ with npm package manager (verify with node --version)
›Active project directory or workspace where you want to add perl-testing
2
Execute installation command
Execute the skills CLI command in your project's root directory to begin installation:
$npx skills add https://github.com/affaan-m/everything-claude-code --skill perl-testingcopy
The skills CLI fetches perl-testing from GitHub repository affaan-m/everything-claude-code and configures it for Cursor.
3
Select Cursor when prompted
The CLI will show a list of available agents. Use arrow keys to navigate and space to select Cursor:
◆ Which agents do you want to install to?
│
│ ── Universal (.agents/skills) ── always included ────
│   • Amp
│   • Antigravity
│   • Cline
│   • Codex
│ ●Cursor(selected)
│   • Cursor
│   • Windsurf
4
Verify installation
Confirm successful installation by checking the skill directory location:
.cursor/skills/perl-testing
Reload or restart Cursor to activate perl-testing. Access the skill through slash commands (e.g., /perl-testing) or your agent's skill management interface.
⚠
Security & Verification Notice
We perform automated surface-level scans (Gen AI Scanner, Socket, Snyk) during installation. These checks detect common vulnerabilities but do not guarantee complete security. Always review skill source code and verify the publisher's reputation before production use.
Skills execute code in your development environment. Always verify the publisher's identity, review recent commits, and test in isolated environments before production deployment.
Additional Resources
›View source code on GitHub›Skills CLI documentation›Learn more about Cursor›What are agent skills?