226 lines
6.1 KiB
Markdown
226 lines
6.1 KiB
Markdown
---
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tags: [React, Testing, Vitest, RTL, Frontend]
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create time: 2026-04-29 22:15
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---
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# 测试
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## 概述
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可靠的测试是大型 React 项目长期维护的基石。本文档以 Vitest + React Testing Library (RTL) 为主，介绍组件单元测试、Hook 测试和集成测试的最佳实践。
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## 测试金字塔
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```mermaid
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graph TB
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A["测试金字塔"]
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A --> B["单元测试 ~70%"]
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A --> C["集成测试 ~20%"]
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A --> D["E2E 测试 ~10%"]
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B --> B1["纯函数 / util"]
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B --> B2["自定义 Hook"]
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B --> B3["原子组件（Button）"]
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C --> C1["多组件交互流程"]
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C --> C2["表单提交 → API → 状态更新"]
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D --> D1["用户旅程：登录→搜索→下单"]
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style B fill:#4FC08D,color:#fff
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style C fill:#F5A87D,color:#000
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style D fill:#61DAFB,color:#000
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```
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## 环境配置
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```jsonc
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// vitest.config.ts
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import { defineConfig } from "vitest/config";
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import react from "@vitejs/plugin-react";
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export default defineConfig({
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plugins: [react()],
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test: {
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environment: "jsdom", // 模拟浏览器 DOM
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setupFiles: "./src/test/setup.ts",
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globals: true,
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},
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});
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```
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```ts
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// src/test/setup.ts
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import "@testing-library/jest-dom/vitest"; // 扩展 expect 匹配器
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import { vi } from "vitest";
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// Mock window.matchMedia（解决媒体查询测试报错）
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Object.defineProperty(window, "matchMedia", {
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writable: true,
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value: vi.fn().mockImplementation(query => ({
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matches: false,
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media: query,
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onchange: null,
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addListener: vi.fn(), // deprecated
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removeListener: vi.fn(), // deprecated
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addEventListener: vi.fn(),
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removeEventListener: vi.fn(),
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dispatchEvent: vi.fn(),
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})),
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});
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```
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## RTL 核心哲学
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> [!tip] RTL 设计原则
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> - **测试行为，不测试实现** — 关注用户能感知到的东西（文本、按钮、网络请求）
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> - **像用户一样思考** — 用 `screen.getByRole("button", { name: "Submit" })` 而非 `.querySelector(".btn-primary"`
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> - **断言明确期望的结果** — 不要测试 state 的值，测试渲染输出
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```tsx
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// ❌ 反例：耦合于内部实现
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expect(component.state.count).toBe(2);
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expect(wrapper.find(Button).length).toBe(1);
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// ✅ 正例：基于用户感知
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const button = screen.getByRole("button", { name: /add/i });
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userEvent.click(button);
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await screen.findByText(/added!/i);
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```
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## 组件单元测试
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### 基础模式
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```tsx
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import { render, screen, fireEvent, waitFor } from "@testing-library/react";
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import userEvent from "@testing-library/user-event";
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import { Counter } from "./Counter";
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describe("<Counter />", () => {
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it("初始显示 0", () => {
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render(<Counter initial={0} />);
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expect(screen.getByText("0")).toBeInTheDocument();
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});
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it("点击按钮后计数增加", async () => {
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render(<Counter initial={0} />);
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const button = screen.getByRole("button");
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await userEvent.click(button);
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expect(screen.getByText("1")).toBeInTheDocument();
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await userEvent.click(button);
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await userEvent.click(button);
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expect(screen.getByText("3")).toBeInTheDocument();
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});
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it("禁用态不可点击", () => {
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render(<Counter disabled initial={0} />);
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const button = screen.getByRole("button");
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expect(button).toBeDisabled();
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});
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});
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```
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### Props 驱动 UI
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```tsx
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describe("<UserCard />", () => {
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it("显示用户基本信息", () => {
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render(<UserCard user={{ name: "Alice", role: "admin" }} />);
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expect(screen.getByText("Alice")).toBeInTheDocument();
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expect(screen.getByRole("img", { name: /avatar/i })).toHaveAttribute("alt", "Alice avatar");
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});
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it("显示操作菜单当 admin 时", () => {
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render(<UserCard user={{ name: "Alice", role: "admin" }} />);
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expect(screen.getByRole("button", { name: /edit/i })).toBeInTheDocument();
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});
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it("普通用户不显示操作菜单", () => {
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render(<UserCard user={{ name: "Bob", role: "user" }} />);
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expect(screen.queryByRole("button", { name: /edit/i })).not.toBeInTheDocument();
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});
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});
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```
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## Mock 异步操作
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```tsx
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it("loading 态在请求完成后消失", async () => {
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vi.mocked(fetch).mockResolvedValueOnce({
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ok: true,
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json: async () => [{ id: 1, name: "Test" }],
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} as Response);
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render(<TodoList />);
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// 等待 loading 态出现再消失
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const spinner = await screen.findByRole("status");
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expect(spinner).toHaveTextContent("Loading...");
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// 数据渲染完成
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const item = await screen.findByText("Test");
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expect(item).toBeInTheDocument();
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});
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it("网络错误显示错误提示", async () => {
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vi.mocked(fetch).mockRejectedValueOnce(new Error("Network error"));
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render(<TodoList />);
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await waitFor(() => {
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expect(screen.getByText("Failed to load")).toBeInTheDocument();
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});
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});
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```
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## Hook 测试
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```tsx
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import { renderHook, act } from "@testing-library/react";
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import { useDebounce } from "../hooks/useDebounce";
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describe("useDebounce", () => {
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beforeEach(() => vi.useFakeTimers());
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afterEach(() => vi.useRealTimers());
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it("值不变时返回原始值", () => {
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const { result } = renderHook(({ value }) => useDebounce(value, 300), {
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initialProps: { value: "hello", delay: 300 },
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});
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expect(result.current).toBe("hello");
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});
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it("延迟后返回新值", async () => {
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const { result, rerender } = renderHook(
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({ value }) => useDebounce(value, 300),
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{ initialProps: { value: "a" } }
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);
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rerender({ value: "b" });
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expect(result.current).toBe("a"); // 尚未变化
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act(() => vi.advanceTimersByTime(300));
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expect(result.current).toBe("b"); // 防抖完成
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});
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});
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```
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## E2E 测试选择
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| 工具 | 适用场景 | 特点 |
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|------|----------|------|
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| **Playwright** | 全功能 E2E（推荐） | 跨浏览器、内置 trace、重试机制 |
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| **Cypress** | 可视化调试友好 | DevTools 体验好、社区活跃 |
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| **Puppeteer** | Google 官方、精细控制 | 底层 API、灵活性高 |
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> [!note] E2E 边界
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> - E2E 只应覆盖**关键用户旅程**（登录、下单、支付）
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> - 不要为每个页面的每个字段写 E2E——那属于集成测试的范畴
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## 关联笔记
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