integration-testing

Integration Testing Rules

Setup

• Use a dedicated test database (never production or development)
• Reset database state before each test suite
• Use transactions for test isolation when possible
• Seed minimal data required for each test

API Integration Tests

describe('POST /api/v1/orders', () => {
  it('should create an order and return 201', async () => {
    const payload = {
      customerId: testCustomer.id,
      items: [{ productId: testProduct.id, quantity: 2 }],
    };

    const response = await request(app)
      .post('/api/v1/orders')
      .set('Authorization', `Bearer ${testToken}`)
      .set('X-Correlation-Id', 'test-123')
      .send(payload)
      .expect(201);

    expect(response.body.data).toMatchObject({
      customerId: testCustomer.id,
      status: 'PENDING',
    });
    expect(response.body.meta.correlationId).toBe('test-123');
  });

  it('should return 400 for invalid payload', async () => {
    const response = await request(app)
      .post('/api/v1/orders')
      .set('Authorization', `Bearer ${testToken}`)
      .send({})
      .expect(400);

    expect(response.body.error.code).toBe('VALIDATION_ERROR');
  });

  it('should return 401 without auth token', async () => {
    await request(app)
      .post('/api/v1/orders')
      .send({ customerId: 'test' })
      .expect(401);
  });
});

Rules

• Test the full request/response cycle — no mocking the HTTP layer
• Test all status codes: success, validation error, auth error, not found
• Test request validation (missing fields, wrong types, boundary values)
• Test pagination, sorting, and filtering
• Verify response envelope format matches API contract
• Clean up test data — don't leave artifacts
• Use a separate port for test server to avoid conflicts