Frontend/Testing Guide

前端测试编写指南

测试要求（强制）

职责边界：Frontend Agent 是测试的编写者，QA Agent 是测试的验证者。

测试金字塔

单元测试编写

组件渲染测试

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// Button.test.tsx
import { render, screen } from '@testing-library/react';
import { Button } from './Button';

describe('Button', () => {
  it('renders with text', () => {
    render(<Button>Click me</Button>);
    expect(screen.getByText('Click me')).toBeInTheDocument();
  });

  it('calls onClick when clicked', () => {
    const handleClick = jest.fn();
    render(<Button onClick={handleClick}>Click</Button>);
    screen.getByText('Click').click();
    expect(handleClick).toHaveBeenCalledTimes(1);
  });

  it('is disabled when disabled prop is true', () => {
    render(<Button disabled>Click</Button>);
    expect(screen.getByText('Click')).toBeDisabled();
  });
});

Hook 测试

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// useCounter.test.ts
import { renderHook, act } from '@testing-library/react';
import { useCounter } from './useCounter';

describe('useCounter', () => {
  it('initializes with default value', () => {
    const { result } = renderHook(() => useCounter());
    expect(result.current.count).toBe(0);
  });

  it('increments count', () => {
    const { result } = renderHook(() => useCounter());
    act(() => {
      result.current.increment();
    });
    expect(result.current.count).toBe(1);
  });
});

表单验证测试

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// LoginForm.test.tsx
import { render, screen, waitFor } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import { LoginForm } from './LoginForm';

describe('LoginForm', () => {
  it('shows validation error for invalid email', async () => {
    render(<LoginForm />);
    const emailInput = screen.getByLabelText('Email');
    
    await userEvent.type(emailInput, 'invalid-email');
    await userEvent.tab(); // Trigger blur
    
    await waitFor(() => {
      expect(screen.getByText('Invalid email format')).toBeInTheDocument();
    });
  });

  it('submits form with valid data', async () => {
    const onSubmit = jest.fn();
    render(<LoginForm onSubmit={onSubmit} />);
    
    await userEvent.type(screen.getByLabelText('Email'), 'user@example.com');
    await userEvent.type(screen.getByLabelText('Password'), 'password123');
    await userEvent.click(screen.getByRole('button', { name: 'Login' }));
    
    await waitFor(() => {
      expect(onSubmit).toHaveBeenCalledWith({
        email: 'user@example.com',
        password: 'password123',
      });
    });
  });
});

集成测试编写

组件交互测试

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// UserList.test.tsx
import { render, screen, waitFor } from '@testing-library/react';
import userEvent from '@testing-library/user-event';
import { UserList } from './UserList';
import { UserProvider } from './UserContext';

describe('UserList integration', () => {
  it('adds new user to list', async () => {
    render(
      <UserProvider>
        <UserList />
      </UserProvider>
    );
    
    // 打开添加用户表单
    await userEvent.click(screen.getByText('Add User'));
    
    // 填写表单
    await userEvent.type(screen.getByLabelText('Name'), 'John Doe');
    await userEvent.type(screen.getByLabelText('Email'), 'john@example.com');
    
    // 提交
    await userEvent.click(screen.getByRole('button', { name: 'Submit' }));
    
    // 验证用户出现在列表中
    await waitFor(() => {
      expect(screen.getByText('John Doe')).toBeInTheDocument();
      expect(screen.getByText('john@example.com')).toBeInTheDocument();
    });
  });
});

状态管理测试

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// store.test.ts
import { renderHook, act } from '@testing-library/react';
import { useStore } from './store';

describe('Store integration', () => {
  it('updates user state across components', () => {
    const { result } = renderHook(() => useStore());
    
    act(() => {
      result.current.setUser({ id: '1', name: 'Alice' });
    });
    
    expect(result.current.user).toEqual({ id: '1', name: 'Alice' });
    
    act(() => {
      result.current.updateUserName('Bob');
    });
    
    expect(result.current.user?.name).toBe('Bob');
  });
});

E2E 测试编写（必须）

完整 Playwright 方法论：详见 Skill(skill: "qa/e2e-playwright")，包含项目初始化、Page Object Model、认证复用、API Mock、视觉回归、多浏览器测试、CI 集成和调试技巧。

E2E 测试必须覆盖

• ✅ 创建流程（如：添加数据）
• ✅ 编辑流程（如：修改数据）
• ✅ 删除流程（如：删除数据）
• ✅ 列表展示（如：查看列表）
• ✅ 核心业务流程

Playwright 示例（Page Object Model）

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// e2e/pages/user-list.page.ts
import { type Page, type Locator } from '@playwright/test';

export class UserListPage {
  private readonly addButton: Locator;
  private readonly table: Locator;

  constructor(private readonly page: Page) {
    this.addButton = page.getByRole('button', { name: '添加用户' });
    this.table = page.getByRole('table');
  }

  async goto() { await this.page.goto('/users'); }
  async clickAddUser() { await this.addButton.click(); }
  getTable() { return this.table; }

  async editUser(name: string) {
    await this.page.getByRole('row', { name }).getByRole('button', { name: '编辑' }).click();
  }
  async deleteUser(name: string) {
    await this.page.getByRole('row', { name }).getByRole('button', { name: '删除' }).click();
  }
  async confirmDelete() {
    await this.page.getByRole('button', { name: '确认' }).click();
  }
}

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// e2e/specs/crud/user-management.spec.ts
import { test, expect } from '@playwright/test';
import { UserListPage } from '../../pages/user-list.page';

test.describe('用户管理 CRUD', () => {
  let userList: UserListPage;

  test.beforeEach(async ({ page }) => {
    userList = new UserListPage(page);
    await userList.goto();
  });

  test('创建 → 编辑 → 删除完整流程', async ({ page }) => {
    // 创建
    await userList.clickAddUser();
    await page.getByLabel('姓名').fill('测试用户');
    await page.getByLabel('邮箱').fill('test@example.com');
    await page.getByRole('button', { name: '提交' }).click();
    await expect(page.getByText('测试用户')).toBeVisible();

    // 编辑
    await userList.editUser('测试用户');
    await page.getByLabel('姓名').fill('修改后的用户');
    await page.getByRole('button', { name: '提交' }).click();
    await expect(page.getByText('修改后的用户')).toBeVisible();

    // 删除
    await userList.deleteUser('修改后的用户');
    await userList.confirmDelete();
    await expect(page.getByText('修改后的用户')).not.toBeVisible();
  });

  test('列表分页展示', async ({ page }) => {
    await expect(userList.getTable()).toBeVisible();
    await page.getByRole('button', { name: 'Next' }).click();
    await expect(page).toHaveURL(/page=2/);
  });
});

定位器优先级

测试最佳实践

测试命名

• 使用描述性的测试名称
• 格式：it('should [expected behavior] when [condition]')
• 示例：it('should show error message when email is invalid')

测试隔离

• 每个测试独立运行，不依赖其他测试
• 使用 beforeEach 设置初始状态
• 使用 afterEach 清理副作用

Mock 策略

• Mock 外部依赖（API、第三方库）
• 不要 Mock 被测试的代码
• 使用 MSW（Mock Service Worker）Mock API

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// mocks/handlers.ts
import { rest } from 'msw';

export const handlers = [
  rest.get('/api/users', (req, res, ctx) => {
    return res(
      ctx.json([
        { id: '1', name: 'Alice' },
        { id: '2', name: 'Bob' },
      ])
    );
  }),
];

边界条件测试

• 空数据：列表为空时的展示
• 错误状态：API 失败时的处理
• 加载状态：数据加载中的展示
• 极限值：最大/最小输入值

无障碍测试

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it('is accessible', async () => {
  const { container } = render(<Button>Click</Button>);
  const results = await axe(container);
  expect(results).toHaveNoViolations();
});

测试覆盖率要求

• 语句覆盖率：≥ 80%
• 分支覆盖率：≥ 75%
• 函数覆盖率：≥ 80%
• 行覆盖率：≥ 80%

运行覆盖率报告：

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npm test -- --coverage

测试报告格式

实现完成后，在输出中包含：

测试添加：

测试结果：

• 通过：25 / 失败：0
• 覆盖率：85%
• E2E 测试：✅ 已编写并通过