testing-strategies

Q: How do I install testing-strategies?

Run npx skills add https://github.com/miles990/claude-software-skills --skill testing-strategies in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/testing-strategies/ (personal) or .claude/skills/testing-strategies/ (project).

by miles990Testing & QA

Unit, integration, E2E testing and TDD practices

Installs: 88
Last 24h: —
Trending rank: —
Security: Not audited

Install

Works with every agent the skills CLI supports.

npx skills add https://github.com/miles990/claude-software-skills --skill testing-strategies

01
Install
Run the command in your project. The CLI asks which agents to install for.
02
Describe the task
Ask your agent for something this skill covers. It loads testing-strategies automatically when relevant.
03
Review the result
The agent follows the SKILL.md steps, scripts and references bundled with the skill.

SKILL.md

The instructions your agent reads when the skill is triggered.

Testing Strategies

Overview

Testing pyramid, patterns, and practices for building reliable software.

Testing Pyramid

           /\
          /  \
         / E2E\        Few, slow, expensive
        /──────\
       /        \
      /Integration\    Some, medium speed
     /──────────────\
    /                \
   /    Unit Tests    \  Many, fast, cheap
  /____________________\

Level	Speed	Scope	Quantity
Unit	Fast (ms)	Single function/class	Many (70%)
Integration	Medium (s)	Multiple components	Some (20%)
E2E	Slow (min)	Full system	Few (10%)

Unit Testing

Structure: Arrange-Act-Assert

describe('calculateDiscount', () => {
  it('applies 10% discount for orders over $100', () => {
    // Arrange
    const order = { items: [{ price: 150 }] };
    const discountService = new DiscountService();

    // Act
    const result = discountService.calculateDiscount(order);

    // Assert
    expect(result).toBe(15);
  });

  it('returns 0 for orders under $100', () => {
    // Arrange
    const order = { items: [{ price: 50 }] };
    const discountService = new DiscountService();

    // Act
    const result = discountService.calculateDiscount(order);

    // Assert
    expect(result).toBe(0);
  });
});

Mocking

// Mock dependencies
const mockEmailService = {
  send: jest.fn().mockResolvedValue({ success: true })
};

const mockUserRepo = {
  findById: jest.fn().mockResolvedValue({ id: '1', email: 'test@example.com' })
};

describe('NotificationService', () => {
  let service: NotificationService;

  beforeEach(() => {
    jest.clearAllMocks();
    service = new NotificationService(mockEmailService, mockUserRepo);
  });

  it('sends email to user', async () => {
    await service.notifyUser('1', 'Hello!');

    expect(mockUserRepo.findById).toHaveBeenCalledWith('1');
    expect(mockEmailService.send).toHaveBeenCalledWith(
      'test@example.com',
      'Hello!'
    );
  });

  it('throws when user not found', async () => {
    mockUserRepo.findById.mockResolvedValue(null);

    await expect(service.notifyUser('999', 'Hello!'))
      .rejects.toThrow('User not found');
  });
});

Testing Edge Cases

describe('parseAge', () => {
  // Happy path
  it('parses valid age string', () => {
    expect(parseAge('25')).toBe(25);
  });

  // Edge cases
  it('handles zero', () => {
    expect(parseAge('0')).toBe(0);
  });

  it('handles boundary values', () => {
    expect(parseAge('1')).toBe(1);
    expect(parseAge('150')).toBe(150);
  });

  // Error cases
  it('throws on negative numbers', () => {
    expect(() => parseAge('-5')).toThrow('Age cannot be negative');
  });

  it('throws on non-numeric input', () => {
    expect(() => parseAge('abc')).toThrow('Invalid age format');
  });

  it('throws on empty string', () => {
    expect(() => parseAge('')).toThrow('Age is required');
  });

  // Null/undefined
  it('throws on null', () => {
    expect(() => parseAge(null as any)).toThrow();
  });
});

Integration Testing

API Testing

import request from 'supertest';
import { app } from '../app';
import { db } from '../database';

describe('POST /api/users', () => {
  beforeEach(async () => {
    await db.users.deleteMany({});
  });

  afterAll(async () => {
    await db.disconnect();
  });

  it('creates a new user', async () => {
    const response = await request(app)
      .post('/api/users')
      .send({
        email: 'test@example.com',
        name: 'Test User'
      })
      .expect(201);

    expect(response.body).toMatchObject({
      id: expect.any(String),
      email: 'test@example.com',
      name: 'Test User'
    });

    // Verify in database
    const user = await db.users.findOne({ email: 'test@example.com' });
    expect(user).not.toBeNull();
  });

  it('returns 400 for invalid email', async () => {
    const response = await request(app)
      .post('/api/users')
      .send({
        email: 'invalid-email',
        name: 'Test User'
      })
      .expect(400);

    expect(response.body.error).toBe('Invalid email format');
  });

  it('returns 409 for duplicate email', async () => {
    // Create first user
    await request(app)
      .post('/api/users')
      .send({ email: 'test@example.com', name: 'First' });

    // Try to create duplicate
    const response = await request(app)
      .post('/api/users')
      .send({ email: 'test@example.com', name: 'Second' })
      .expect(409);

    expect(response.body.error).toBe('Email already exists');
  });
});

Database Testing with Testcontainers

import { PostgreSqlContainer } from '@testcontainers/postgresql';
import { Pool } from 'pg';

describe('UserRepository', () => {
  let container: StartedPostgreSqlContainer;
  let pool: Pool;
  let repo: UserRepository;

  beforeAll(async () => {
    container = await new PostgreSqlContainer().start();
    pool = new Pool({ connectionString: container.getConnectionUri() });
    await runMigrations(pool);
    repo = new UserRepository(pool);
  }, 60000);

  afterAll(async () => {
    await pool.end();
    await container.stop();
  });

  beforeEach(async () => {
    await pool.query('TRUNCATE users CASCADE');
  });

  it('creates and retrieves user', async () => {
    const created = await repo.create({
      email: 'test@example.com',
      name: 'Test'
    });

    const found = await repo.findById(created.id);

    expect(found).toEqual(created);
  });
});

E2E Testing

Playwright

import { test, expect } from '@playwright/test';

test.describe('User Authentication', () => {
  test('successful login flow', async ({ page }) => {
    await page.goto('/login');

    // Fill form
    await page.fill('[data-testid="email-input"]', 'user@example.com');
    await page.fill('[data-testid="password-input"]', 'password123');

    // Submit
    await page.click('[data-testid="login-button"]');

    // Verify redirect to dashboard
    await expect(page).toHaveURL('/dashboard');
    await expect(page.locator('[data-testid="welcome-message"]'))
      .toContainText('Welcome, user@example.com');
  });

  test('shows error for invalid credentials', async ({ page }) => {
    await page.goto('/login');

    await page.fill('[data-testid="email-input"]', 'wrong@example.com');
    await page.fill('[data-testid="password-input"]', 'wrongpassword');
    await page.click('[data-testid="login-button"]');

    await expect(page.locator('[data-testid="error-message"]'))
      .toBeVisible()
      .toContainText('Invalid credentials');
  });
});

test.describe('Shopping Cart', () => {
  test('add item and checkout', async ({ page }) => {
    // Setup - login
    await page.goto('/login');
    await page.fill('[data-testid="email-input"]', 'buyer@example.com');
    await page.fill('[data-testid="password-input"]', 'password');
    await page.click('[data-testid="login-button"]');

    // Browse products
    await page.goto('/products');
    await page.click('[data-testid="product-1"] [data-testid="add-to-cart"]');

    // Verify cart
    await expect(page.locator('[data-testid="cart-count"]')).toHaveText('1');

    // Checkout
    await page.click('[data-testid="cart-icon"]');
    await page.click('[data-testid="checkout-button"]');

    // Fill shipping
    await page.fill('[data-testid="address"]', '123 Test St');
    await page.click('[data-testid="place-order"]');

    // Verify success
    await expect(page).toHaveURL(/\/orders\/\d+/);
    await expect(page.locator('[data-testid="order-status"]'))
      .toContainText('Order Confirmed');
  });
});

Visual Regression Testing

import { test, expect } from '@playwright/test';

test('homepage visual regression', async ({ page }) => {
  await page.goto('/');

  // Wait for dynamic content
  await page.waitForSelector('[data-testid="hero-section"]');

  // Take screenshot and compare
  await expect(page).toHaveScreenshot('homepage.png', {
    maxDiffPixels: 100,
    threshold: 0.2
  });
});

test('responsive design', async ({ page }) => {
  await page.setViewportSize({ width: 375, height: 667 }); // iPhone SE
  await page.goto('/');

  await expect(page).toHaveScreenshot('homepage-mobile.png');
});

Test-Driven Development (TDD)

Red-Green-Refactor Cycle

// 1. RED - Write failing test first
test('passwordValidator rejects passwords without numbers', () => {
  const result = validatePassword('NoNumbers!');
  expect(result.valid).toBe(false);
  expect(result.errors).toContain('Must contain at least one number');
});

// 2. GREEN - Write minimal code to pass
function validatePassword(password: string): ValidationResult {
  const errors: string[] = [];

  if (!/\d/.test(password)) {
    errors.push('Must contain at least one number');
  }

  return { valid: errors.length === 0, errors };
}

// 3. REFACTOR - Improve code quality
const VALIDATION_RULES = [
  { pattern: /\d/, message: 'Must contain at least one number' },
  { pattern: /[A-Z]/, message: 'Must contain at least one uppercase letter' },
  { pattern: /[a-z]/, message: 'Must contain at least one lowercase letter' },
  { pattern: /.{8,}/, message: 'Must be at least 8 characters' }
];

function validatePassword(password: string): ValidationResult {
  const errors = VALIDATION_RULES
    .filter(rule => !rule.pattern.test(password))
    .map(rule => rule.message);

  return { valid: errors.length === 0, errors };
}

Testing Patterns

Test Fixtures

// fixtures/users.ts
export const validUser = {
  email: 'test@example.com',
  name: 'Test User',
  role: 'user'
};

export const adminUser = {
  ...validUser,
  role: 'admin',
  email: 'admin@example.com'
};

// In tests
import { validUser, adminUser } from '../fixtures/users';

describe('UserService', () => {
  it('creates user with valid data', async () => {
    const result = await service.create(validUser);
    expect(result.email).toBe(validUser.email);
  });
});

Factory Functions

// factories/user.factory.ts
import { faker } from '@faker-js/faker';

export function createUser(overrides: Partial<User> = {}): User {
  return {
    id: faker.string.uuid(),
    email: faker.internet.email(),
    name: faker.person.fullName(),
    createdAt: faker.date.past(),
    ...overrides
  };
}

// In tests
it('handles users with long names', () => {
  const user = createUser({ name: 'A'.repeat(100) });
  const result = formatUserCard(user);
  expect(result.displayName).toHaveLength(50); // Truncated
});

Testing Async Code

// Async/await
it('fetches user data', async () => {
  const user = await userService.getById('123');
  expect(user.name).toBe('John');
});

// Promises
it('fetches user data', () => {
  return userService.getById('123').then(user => {
    expect(user.name).toBe('John');
  });
});

// Testing rejected promises
it('throws on invalid id', async () => {
  await expect(userService.getById('invalid'))
    .rejects.toThrow('User not found');
});

// Waiting for side effects
it('debounces search input', async () => {
  const onSearch = jest.fn();
  render(<SearchBox onSearch={onSearch} debounceMs={300} />);

  await userEvent.type(screen.getByRole('textbox'), 'test');

  // Should not have called yet
  expect(onSearch).not.toHaveBeenCalled();

  // Wait for debounce
  await waitFor(() => {
    expect(onSearch).toHaveBeenCalledWith('test');
  }, { timeout: 500 });
});

Code Coverage

Coverage Metrics

Metric	What It Measures
Line	Percentage of lines executed
Branch	Percentage of if/else branches taken
Function	Percentage of functions called
Statement	Percentage of statements executed

Jest Configuration

// jest.config.js
module.exports = {
  collectCoverageFrom: [
    'src/**/*.{ts,tsx}',
    '!src/**/*.d.ts',
    '!src/**/*.stories.tsx',
    '!src/test/**'
  ],
  coverageThreshold: {
    global: {
      branches: 80,
      functions: 80,
      lines: 80,
      statements: 80
    }
  }
};

Related Skills

[[code-quality]] - Writing testable code
[[devops-cicd]] - CI integration
[[performance-optimization]] - Performance testing

Sharp Edges（常見陷阱）

這些是測試中最常見且代價最高的錯誤

SE-1: 測試實作而非行為

嚴重度: high
情境: 測試過度耦合內部實作，重構時測試全部壞掉
原因: 測試私有方法、mock 太細、驗證內部狀態
症狀:
- 改了一行程式碼，10 個測試失敗
- 測試檔案比程式碼還長
- 重構時花更多時間修測試
檢測: expect.*\.toHaveBeenCalledTimes\(\d{2,}\)|mock.*private|spy.*internal
解法: 測試公開 API/行為、使用 black-box testing、減少 mock 數量

SE-2: 假陽性測試 (False Positive)

嚴重度: critical
情境: 測試永遠通過，但實際上沒有驗證任何東西
原因: 忘記 await、expect 沒有執行、條件判斷錯誤
症狀:
- 測試通過但 bug 仍然存在
- 刪掉測試中的關鍵 assertion 測試還是通過
- Coverage 高但信心低
檢測: it\(.*\{\s*\}\)|expect\(.*\)(?!\.)|\.resolves(?!\.)|\.rejects(?!\.)
解法: TDD（先寫失敗的測試）、review 測試程式碼、使用 ESLint no-floating-promises

SE-3: Flaky Tests（不穩定測試）

嚴重度: high
情境: 測試有時通過有時失敗，沒有程式碼變更
原因: 依賴時間、依賴外部服務、競態條件、共享狀態
症狀:
- CI 需要 retry 才能通過
- 本地通過但 CI 失敗
- 團隊開始忽略失敗的測試
檢測: new Date\(\)|Date\.now\(\)|setTimeout.*\d{4,}|sleep\(\d+\)
解法: 使用 fake timers、隔離測試狀態、避免 hard-coded delays、mock 外部依賴

SE-4: 測試金字塔倒置

嚴重度: medium
情境: E2E 測試太多，單元測試太少，CI 超慢
原因: 「E2E 測試更接近真實」的誤解、不想寫單元測試
症狀:
- CI 跑 30+ 分鐘
- 測試失敗難以定位問題
- E2E 測試經常 flaky
檢測: describe.*E2E|playwright.*test|cypress.*it (數量遠超 unit test)
解法: 遵循 70% unit / 20% integration / 10% E2E 比例、E2E 只測關鍵路徑

SE-5: 過度 Mocking

嚴重度: medium
情境: Mock 太多導致測試失去意義，只是在測試 mock
原因: 為了隔離而 mock 所有依賴、測試執行時間焦慮
症狀:
- 測試通過但整合時失敗
- Mock 的行為與真實行為不符
- 更新依賴後 mock 過時
檢測: jest\.mock.*jest\.mock.*jest\.mock|mock\(.*\).*mock\(.*\).*mock\(
解法: 只 mock 外部依賴（網路、檔案系統）、使用真實的 in-memory 實作、寫更多整合測試

Validations

V-1: 禁止空的測試

類型: regex
嚴重度: critical
模式: (it|test)\s*\([^)]+,\s*(async\s*)?\(\)\s*=>\s*\{\s*\}\s*\)
訊息: Empty test detected - test has no assertions
修復建議: Add meaningful assertions with expect()
適用: *.test.ts, *.test.js, *.spec.ts, *.spec.js

V-2: 測試缺少 assertion

類型: regex
嚴重度: high
模式: (it|test)\s*\([^)]+,\s*(async\s*)?\(\)\s*=>\s*\{[^}]*\}(?![^}]*expect)
訊息: Test without expect() assertion may be a false positive
修復建議: Add at least one expect() assertion
適用: *.test.ts, *.test.js, *.spec.ts, *.spec.js

V-3: 禁止 fit/fdescribe (focused tests)

類型: regex
嚴重度: critical
模式: \b(fit|fdescribe|it\.only|describe\.only|test\.only)\s*\(
訊息: Focused test will skip other tests in CI
修復建議: Remove f prefix or .only before committing
適用: *.test.ts, *.test.js, *.spec.ts, *.spec.js

V-4: 禁止 skip tests 無說明

類型: regex
嚴重度: medium
模式: (xit|xdescribe|it\.skip|describe\.skip|test\.skip)\s*\([^)]+\)
訊息: Skipped test without documented reason
修復建議: Add comment explaining why test is skipped and tracking issue
適用: *.test.ts, *.test.js, *.spec.ts, *.spec.js

V-5: 測試中使用 setTimeout

類型: regex
嚴重度: high
模式: setTimeout\s*\(\s*[^,]+,\s*\d{3,}\s*\)
訊息: Hard-coded delays in tests cause flakiness and slow tests
修復建議: Use jest.useFakeTimers() or waitFor() from testing-library
適用: *.test.ts, *.test.js, *.spec.ts, *.spec.js

FAQ

What does the testing-strategies skill do?

Unit, integration, E2E testing and TDD practices

How do I install testing-strategies?

Run npx skills add https://github.com/miles990/claude-software-skills --skill testing-strategies in your project. The skills CLI detects the agents you use and copies the skill into the right folder. For Claude Code you can also place the skill folder at ~/.claude/skills/testing-strategies/ (personal) or .claude/skills/testing-strategies/ (project).

Which AI agents can use testing-strategies?

Any agent that supports the open Agent Skills format (a folder with a SKILL.md file), including Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, Windsurf, Cline, OpenCode and more.

Is testing-strategies safe to install?

No partner security audit is available yet. Skills can run commands and scripts, so read the SKILL.md and any bundled files before installing.

Who maintains testing-strategies?

It is published by miles990 in miles990/claude-software-skills. It has 88 recorded installs.

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testing-strategies

Install

Install

Describe the task

Review the result

SKILL.md

Testing Strategies

Overview

Testing Pyramid

Unit Testing

Structure: Arrange-Act-Assert

Mocking

Testing Edge Cases

Integration Testing

API Testing

Database Testing with Testcontainers

E2E Testing

Playwright

Visual Regression Testing

Test-Driven Development (TDD)

Red-Green-Refactor Cycle

Testing Patterns

Test Fixtures

Factory Functions

Testing Async Code

Code Coverage

Coverage Metrics

Jest Configuration

Related Skills

Sharp Edges（常見陷阱）

SE-1: 測試實作而非行為

SE-2: 假陽性測試 (False Positive)

SE-3: Flaky Tests（不穩定測試）

SE-4: 測試金字塔倒置

SE-5: 過度 Mocking

Validations

V-1: 禁止空的測試

V-2: 測試缺少 assertion

V-3: 禁止 fit/fdescribe (focused tests)

V-4: 禁止 skip tests 無說明

V-5: 測試中使用 setTimeout

FAQ

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