Bun test

Bun:test — built-in test runner with Jest-like API, runs in Bun runtime.

TestingSimple

Stack Components

Frameworkbun:test

RuntimeBun

Why

Zero config, 5x faster than Jest, native TS/JSX, snapshot support. Vitest replaced Jest for Vite projects, running 3x faster with native ESM.

Playwright became the #1 E2E tool in 2024, surpassing Cypress with cross-browser support and auto-waiting.

When

Use for Bun projects. Avoid for Node-specific code.

How

1. Install Bun 2. Write *.test.ts 3. bun test 4. View results 5. Add environment configuration — cp .env.example .env && edit values 6. Run tests — npm test or pnpm test to verify setup 7. Deploy — git push to trigger CI/CD or manual deploy

Example

import { test, expect } from 'bun:test'; test('math', () => { expect(2 + 2).toBe(4); });

Common Problems

⚠Node API differences — use bun:shims
⚠Coverage — use bun test --coverage
⚠Configuration drift between environments — use infrastructure-as-code (Terraform/Pulumi) to keep dev/staging/prod identical

Best Practices

✓Use mock.module for ESM mocking
✓Leverage bun:test for fast CI
✓Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit

FAQ

What is Bun test and what projects is it for?

Bun:test — built-in test runner with Jest-like API, runs in Bun runtime. It pairs layered technologies for end-to-end type safety and out-of-the-box deploys, fitting everything from MVPs to production SaaS.

How do I spin up a working demo with Bun test in 10 minutes?

Two steps: (1) Install Bun; (2) Write *.test.ts. Get the local dev server running, then wire one real data source to verify the end-to-end loop.

What is the most common pitfall with Bun test and how do I avoid it?

The most common pitfall is: Node API differences — use bun:shims. Avoid it by adding the matching checklist to your PR template and running type-check + lint + unit tests in CI — three gates before merge.

What are the best practices for Bun test?

Best practices for Bun test include: Use mock.module for ESM mocking; Leverage bun:test for fast CI; Set up health checks and graceful shutdown — handle SIGTERM to drain in-flight requests before exit. The first one — "Use mock.module for ESM mocking" — should be set up at project init to avoid costly rework later.

When should I NOT choose Bun test?

Pick something else in three cases: (1) the team has zero experience with the core framework and the deadline is tight (learning-curve risk); (2) it's a pure content/marketing site (Astro is lighter); (3) you need very high throughput (>10k RPS) or strict-consistency microservices (Go/Rust). Bun test shines for mid-to-high complexity full-stack and API work — don't over-engineer simple static pages with it.