TDD with TestLink

This tutorial series teaches you how to integrate TestLink into your Test-Driven Development workflow. You'll learn when and how to add links during the TDD cycle.

What is TDD?

Test-Driven Development is a software development approach where you:

1. Write a failing test (Red)
2. Write minimal code to pass the test (Green)
3. Refactor the code (Refactor)

This cycle repeats for each piece of functionality.

How TestLink Enhances TDD

TestLink adds explicit traceability to TDD:

• Document intent - Links show which tests verify which production code
• Prevent drift - Validation catches broken links during refactoring
• Enable navigation - Jump between production code and tests in your IDE

When to Add Links in TDD

The key question is: when during the TDD cycle should you add links?

Phase	Add Links?	Why
Red (write test)	Yes - test side	Declare what you're testing
Green (make it pass)	Yes - production side	Document coverage
Refactor	Update if needed	Keep links accurate

Tutorials in This Series

Tutorial	What You'll Learn
Red-Green-Refactor	The classic TDD cycle with links at each phase
Placeholders	Using @placeholder markers for fast iteration
Complete Example	Build a PriceCalculator from scratch using TDD

Quick Start Example

Here's a preview of TDD with TestLink:

Step 1: Write a failing test with link

test('calculates discount for premium users', function () {
    $calculator = new PriceCalculator();

    expect($calculator->calculateDiscount('premium', 100))->toBe(20);
})->linksAndCovers(PriceCalculator::class.'::calculateDiscount');

Step 2: Write minimal production code with link

use TestFlowLabs\TestingAttributes\TestedBy;

class PriceCalculator
{
    #[TestedBy('Tests\PriceCalculatorTest', 'calculates discount for premium users')]
    public function calculateDiscount(string $userType, int $amount): int
    {
        if ($userType === 'premium') {
            return (int) ($amount * 0.2);
        }

        return 0;
    }
}

Step 3: Validate

./vendor/bin/testlink validate
✓ All links are valid!

Automate with Sync

Instead of manually adding links to both sides, you can add a link to one side and let testlink sync propagate it:

# Add #[TestedBy] to production, then run:
./vendor/bin/testlink sync

# Or add linksAndCovers() to test, then run:
./vendor/bin/testlink sync

See How-to: Sync Links Automatically for details.

Prerequisites

Before starting these tutorials:

• Complete Getting Started
• Complete Your First Bidirectional Link
• Have a basic understanding of TDD concepts

Ready to begin? Start with Red-Green-Refactor!