integration-testing

SKILL.md

Integration Testing

Table of Contents

Overview

When to Use

Quick Start

Reference Guides

Best Practices

Overview

Integration testing validates that different components, modules, or services work correctly together. Unlike unit tests that isolate single functions, integration tests verify the interactions between multiple parts of your system including databases, APIs, external services, and infrastructure.

When to Use

Testing API endpoints with real database connections

Verifying service-to-service communication

Validating data flow across multiple layers

Testing repository/DAO layer with actual databases

Checking authentication and authorization flows

Verifying message queue consumers and producers

Testing third-party service integrations

Quick Start

Minimal working example:

// test/api/users.integration.test.js
const request = require("supertest");
const app = require("../../src/app");
const { setupTestDB, teardownTestDB } = require("../helpers/db");

describe("User API Integration Tests", () => {
  beforeAll(async () => {
    await setupTestDB();
  });

  afterAll(async () => {
    await teardownTestDB();
  });

  beforeEach(async () => {
    await clearUsers();
  });

  describe("POST /api/users", () => {
    it("should create a new user with valid data", async () => {
      const userData = {
        email: "test@example.com",
        name: "Test User",
        password: "SecurePass123!",
      };
// ... (see reference guides for full implementation)

Reference Guides

Detailed implementations in the references/ directory:

Guide
Contents

API Integration Testing
API Integration Testing

Database Integration Testing
Database Integration Testing

External Service Integration
External Service Integration

Message Queue Integration
Message Queue Integration

Best Practices

✅ DO

Use real databases in integration tests (in-memory or containers)

Test actual HTTP requests, not mocked responses

Verify database state after operations

Test transaction boundaries and rollbacks

Include authentication/authorization in tests

Test error scenarios and edge cases

Use test containers for isolated environments

Clean up data between tests

❌ DON'T

Mock database connections in integration tests

Skip testing error paths

Leave test data in databases

Use production databases for testing

Ignore transaction management

Test only happy paths

Share state between tests

Hardcode URLs or credentials

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