Module 09: Integration Testing

Duration: 2-3 hours | Difficulty: Intermediate

Integration tests verify that different parts of your application work together correctly. They catch bugs that unit tests miss.

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What You'll Learn

• Setting up test databases
• Testing API endpoints
• Testing service interactions
• Database transaction testing
• CI/CD integration

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Module Lessons

Lesson	Topic	Duration
09.1 Test Databases	Setting up isolated test databases	45 min
09.2 API Testing	Testing REST endpoints	45 min
09.3 Service Integration	Testing component interactions	45 min
09.4 CI Integration	Running tests in CI/CD	30 min

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Integration Test Characteristics

Speed:        🏃 Moderate (seconds)
Count:        📊 Some (dozens/hundreds)
Scope:        🔗 Multiple components
Dependencies: ✅ Real (test instances)
Cost:         💵 Moderate

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Example Integration Test

describe('POST /api/orders', () => {
  beforeEach(async () => {
    await testDb.truncate();
  });

  it('should create order and update inventory', async () => {
    // Setup: Create product with stock
    await testDb.products.create({
      id: 'laptop',
      stock: 10
    });

    // Act: Create order via API
    const response = await request(app)
      .post('/api/orders')
      .send({ productId: 'laptop', quantity: 2 });

    // Assert: Order created
    expect(response.status).toBe(201);

    // Assert: Inventory updated
    const product = await testDb.products.findById('laptop');
    expect(product.stock).toBe(8);
  });
});

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Prerequisites

Before starting:

• ✅ Completed Module 08
• ✅ Basic database knowledge
• ✅ Understanding of REST APIs

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Let's Begin

Ready to test component interactions?

→ Start Lesson 09.1: Test Databases