bun-test-lifecycle

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Bun Test Lifecycle

Bun Test 生命周期

Bun supports Jest-compatible lifecycle hooks for test setup and teardown.

Bun 支持与 Jest 兼容的生命周期钩子，用于测试的初始化和清理工作。

Lifecycle Hooks

生命周期钩子

typescript

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");
});

typescript

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");
});

Hook Execution Order

钩子执行顺序

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

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

Nested Describe Hooks

嵌套 Describe 钩子

typescript

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

typescript

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

Async Hooks

异步钩子

typescript

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

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

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

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

typescript

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

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

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

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

Timeout for Hooks

钩子超时设置

typescript

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

typescript

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

Preload Scripts

预加载脚本

Use

--preload

for global setup across all test files:

bash

bun test --preload ./setup.ts

使用

--preload

实现所有测试文件的全局初始化：

bash

bun test --preload ./setup.ts

setup.ts

typescript

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",
};

typescript

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",
};

Configure in bunfig.toml

在 bunfig.toml 中配置

toml

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

toml

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

Common Patterns

常见模式

Database Setup

数据库初始化

typescript

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
});

typescript

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
});

Server Setup

服务端初始化

typescript

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}`;
});

afterAll(() => {
  server.stop();
});

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

typescript

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}`;
});

afterAll(() => {
  server.stop();
});

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

Mock Setup

Mock 配置

typescript

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();
});

typescript

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();
});

Environment Variables

环境变量配置

typescript

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;
});

typescript

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;
});

Shared Fixtures

共享夹具

typescript

// 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);
});

typescript

// 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);
});

Hook Errors

钩子错误

If a hook throws, all tests in that describe block fail:

typescript

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

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

如果钩子抛出异常，该 describe 块中的所有测试都会失败：

typescript

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

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

Common Errors

常见错误

Error	Cause	Fix
`beforeAll timeout`	Slow async setup	Increase timeout
`Hook not called`	Wrong scope	Check hook placement
`Cleanup not run`	afterAll skipped	Ensure no throws in tests
`State leak`	Missing cleanup	Add proper afterEach

错误	原因	修复方案
`beforeAll timeout`	异步初始化过慢	增加超时时间
`Hook not called`	作用域错误	检查钩子放置位置
`Cleanup not run`	afterAll 被跳过	确保测试中没有抛出异常
`State leak`	缺失清理步骤	添加合适的 afterEach

When to Load References

何时加载参考文档

Load

references/preload-scripts.md

when:

Complex global setup
Multiple preload files

Load

references/fixtures.md

when:

Reusable test fixtures
Factory patterns

当满足以下条件时加载

references/preload-scripts.md

：

复杂的全局初始化
多个预加载文件

当满足以下条件时加载

references/fixtures.md

：

可复用的测试夹具
工厂模式