bun-test-lifecycle

Bun 测试生命周期

Bun 支持与 Jest 兼容的生命周期钩子，用于测试的设置和清理。

生命周期钩子

import { test, expect, beforeAll, afterAll, beforeEach, afterEach } from "bun:test";

let db: Database;
let testData: any;

// Runs once before all tests in file
beforeAll(async () => {
  db = await Database.connect();
});

// Runs once after all tests in file
afterAll(async () => {
  await db.close();
});

// Runs before each test
beforeEach(() => {
  testData = { id: 1, name: "test" };
});

// Runs after each test
afterEach(() => {
  testData = null;
});

test("example", () => {
  expect(testData.name).toBe("test");
});

钩子执行顺序

beforeAll
  ├── beforeEach
  │   └── test 1
  │   └── afterEach
  ├── beforeEach
  │   └── test 2
  │   └── afterEach
afterAll

嵌套 describe 钩子

import { describe, test, beforeAll, beforeEach, afterEach, afterAll } from "bun:test";

describe("outer", () => {
  beforeAll(() => console.log("1. outer beforeAll"));
  afterAll(() => console.log("6. outer afterAll"));
  beforeEach(() => console.log("2. outer beforeEach"));
  afterEach(() => console.log("5. outer afterEach"));

  describe("inner", () => {
    beforeEach(() => console.log("3. inner beforeEach"));
    afterEach(() => console.log("4. inner afterEach"));

    test("test", () => {
      console.log("test runs here");
    });
  });
});

// Output:
// 1. outer beforeAll
// 2. outer beforeEach
// 3. inner beforeEach
// test runs here
// 4. inner afterEach
// 5. outer afterEach
// 6. outer afterAll

异步钩子

beforeAll(async () => {
  await setupDatabase();
});

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

afterEach(async () => {
  await clearTestData();
});

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

钩子超时

// Set timeout for slow setup
beforeAll(async () => {
  await slowSetup();
}, 30000); // 30 seconds

预加载脚本

使用 --preload 为所有测试文件进行全局设置：

bun test --preload ./setup.ts

setup.ts

import { beforeAll, afterAll } from "bun:test";

// Global setup
beforeAll(() => {
  console.log("Global setup runs before all test files");
});

// Global teardown
afterAll(() => {
  console.log("Global teardown runs after all test files");
});

// Set global variables
globalThis.testConfig = {
  apiUrl: "http://localhost:3000",
};

在 bunfig.toml 中配置

[test]
preload = ["./test/setup.ts"]

常见模式

数据库设置

import { beforeAll, afterAll, beforeEach, afterEach } from "bun:test";

let db: Database;

beforeAll(async () => {
  db = await Database.connect(process.env.TEST_DB_URL);
  await db.migrate();
});

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

beforeEach(async () => {
  await db.beginTransaction();
});

afterEach(async () => {
  await db.rollback(); // Reset state
});

服务端设置

import { beforeAll, afterAll } from "bun:test";

let server: Server;
let baseUrl: string;

beforeAll(async () => {
  server = Bun.serve({
    port: 0, // Random available port
    fetch: app.fetch,
  });
  baseUrl = `http://localhost:${server.port}`;
});

// Bun 1.2+: server.stop() returns a Promise that resolves once in-flight
// connections have closed — await it so the test process doesn't exit early.
afterAll(async () => {
  await server.stop();
});

test("api works", async () => {
  const res = await fetch(`${baseUrl}/api/health`);
  expect(res.ok).toBe(true);
});

Mock 设置

import { beforeEach, afterEach, spyOn } from "bun:test";

let fetchSpy: ReturnType<typeof spyOn>;

beforeEach(() => {
  fetchSpy = spyOn(global, "fetch").mockResolvedValue(
    new Response(JSON.stringify({ ok: true }))
  );
});

afterEach(() => {
  fetchSpy.mockRestore();
});

环境变量

import { beforeAll, afterAll } from "bun:test";

const originalEnv = process.env;

beforeAll(() => {
  process.env = {
    ...originalEnv,
    NODE_ENV: "test",
    API_KEY: "test-key",
  };
});

afterAll(() => {
  process.env = originalEnv;
});

共享测试夹具

// fixtures.ts
export async function createTestUser() {
  return { id: 1, name: "Test User" };
}

export async function cleanupTestUser(user: any) {
  // cleanup logic
}

// test file
import { createTestUser, cleanupTestUser } from "./fixtures";

let user: any;

beforeEach(async () => {
  user = await createTestUser();
});

afterEach(async () => {
  await cleanupTestUser(user);
});

钩子错误

如果钩子抛出错误，该 describe 块中的所有测试都会失败：

beforeAll(() => {
  throw new Error("Setup failed");
});

// All tests in this file will fail
test("will fail", () => {
  expect(true).toBe(true);
});

常见错误

错误	原因	解决方法
beforeAll timeout	异步设置缓慢	增加超时时间
Hook not called	作用域错误	检查钩子的位置
Cleanup not run	跳过了 afterAll	确保测试中没有抛出错误
State leak	缺少清理	添加适当的 afterEach

何时加载参考文档

遇到以下情况时，加载 references/preload-scripts.md：

• 复杂的全局设置
• 多个预加载文件

遇到以下情况时，加载 references/fixtures.md：

• 可复用的测试夹具
• 工厂模式