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bun-test-lifecycle · claude-skills · Flowy
Use for test lifecycle hooks: beforeAll, afterAll, beforeEach, afterEach, fixtures, preload.
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Use for test lifecycle hooks: beforeAll, afterAll, beforeEach, afterEach, fixtures, preload. 📦 Ships with claude-skills
</> SKILL.md
bun-test-lifecycle.SKILL.md
---
name : bun-test-lifecycle
description : "Use for test lifecycle hooks: beforeAll, afterAll, beforeEach, afterEach, fixtures, preload."
metadata:
version: "1.0.0"
license : MIT
---
# Bun Test Lifecycle
Bun supports Jest-compatible lifecycle hooks for test setup and teardown.
## Lifecycle Hooks
```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");
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});
```
## Hook Execution Order
```
beforeAll
├── beforeEach
│ └── test 1
│ └── afterEach
├── beforeEach
│ └── test 2
│ └── afterEach
afterAll
```
## Nested Describe Hooks
```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
```typescript
beforeAll(async () => {
await setupDatabase();
});
beforeEach(async () => {
await seedTestData();
});
afterEach(async () => {
await clearTestData();
});
afterAll(async () => {
await teardownDatabase();
});
```
## Timeout for Hooks
```typescript
// Set timeout for slow setup
beforeAll(async () => {
await slowSetup();
}, 30000); // 30 seconds
```
## Preload Scripts
Use `--preload` for global setup across all test files:
```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",
};
```
### Configure in bunfig.toml
```toml
[test]
preload = ["./test/setup.ts"]
```
## Common Patterns
### Database Setup
```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
```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
```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
```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
```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
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);
});
```
## Common Errors
| 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 |
## When to Load References
Load `references/preload-scripts.md` when:
- Complex global setup
- Multiple preload files
Load `references/fixtures.md` when:
- Reusable test fixtures
- Factory patterns
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