Vitest vs Bun test vs Jest: test runner 2026

TL;DR

• Vitest: Recommended untuk Node project, ekosistem Jest-compatible
• Bun test: Recommended untuk Bun runtime project, native + super cepat
• Jest: Skip untuk project baru, only maintain legacy

Konteks

3 project saya 2024-2026:

• SaaS billing fotograf (Node + Hono): Vitest
• SaaS klinik dental (Bun + Hono): Bun test
• Internal tool Laravel + React: Vitest (untuk React frontend)

Performance benchmark

Same test suite: 120 test cases (unit + integration), TypeScript, mock fetch.

Runner	Cold run	Hot run (watch)
Jest	8.4s	2.8s
Vitest	2.1s	0.4s
Bun test	0.9s	0.2s

Bun test paling cepat (native). Vitest signifikan lebih cepat dari Jest karena ESM-first + Vite-based.

Vitest

Pro

• Jest-compatible API: 95% Jest test bisa run di Vitest tanpa change
• ESM-first: tidak butuh @babel/preset-env + CommonJS dance
• Vite ecosystem: kalau Anda pakai Vite (or Astro), config shared
• Watch mode: instant re-run via Vite HMR
• UI mode: visual test runner (run via vitest --ui)
• Active development: weekly release, fix bug fast

Con

• Bundle size lebih besar dari Bun test
• TypeScript support OK tapi butuh tsconfig sync
• Mock API slightly less elegant dari Bun test

Example

import { describe, it, expect, vi } from 'vitest';
import { calculateBill } from './bill';

describe('calculateBill', () => {
  it('compute tax correctly', () => {
    expect(calculateBill(100, 0.11)).toBe(111);
  });

  it('handles network error', async () => {
    const fetch = vi.spyOn(globalThis, 'fetch').mockRejectedValue(new Error('Network'));
    await expect(getRates()).rejects.toThrow('Network');
  });
});

Bun test

Pro

• Native ke Bun runtime: tidak butuh dependency tambahan
• Paling cepat: 2-3x faster dari Vitest
• Same syntax as Jest/Vitest: minimal learning curve
• Built-in coverage (via bun test --coverage)
• Snapshot test built-in

Con

• Bun-only: tidak run di Node CI yang tidak install Bun
• Ecosystem kecil: less third-party reporter, plugin, integration
• TypeScript config kadang issue: subtle behavior differences dari tsc

Example

import { describe, it, expect, mock } from 'bun:test';
import { calculateBill } from './bill';

describe('calculateBill', () => {
  it('compute tax correctly', () => {
    expect(calculateBill(100, 0.11)).toBe(111);
  });

  it('handles network error', async () => {
    const fetch = mock(() => Promise.reject(new Error('Network')));
    globalThis.fetch = fetch;
    await expect(getRates()).rejects.toThrow('Network');
  });
});

Hampir identical dengan Vitest. Migration trivial.

Jest

Pro

• Most mature: 10+ tahun, paling banyak ecosystem
• Familiar: most React tutorial pakai Jest
• Stable: bug rare, behavior predictable

Con

• Slow di 2026: 4-10x lebih lambat dari Vitest/Bun
• CommonJS-first: butuh transform untuk ESM modern code
• Config kompleks: babel + jest.config.js + transformers
• Stagnant innovation: feature baru release lambat

Migration

Jest → Vitest

bun remove jest @types/jest babel-jest jest-environment-jsdom
bun add -d vitest @vitest/ui happy-dom

Update package.json:

{
  "scripts": {
    "test": "vitest",
    "test:ui": "vitest --ui",
    "coverage": "vitest --coverage"
  }
}

Create vitest.config.ts:

import { defineConfig } from 'vitest/config';

export default defineConfig({
  test: {
    environment: 'happy-dom',  // atau 'node' atau 'jsdom'
    globals: true,
  },
});

Update test files: change from 'jest' → from 'vitest'. Most other API same.

Time: 1-2 jam untuk 100-200 test file.

Vitest → Bun test

# Remove vitest
bun remove vitest @vitest/ui happy-dom

# Update import
# from 'vitest' → from 'bun:test'

# Update test script
# "test": "vitest" → "test": "bun test"

Bun test cover most Vitest API. Some edge case (custom matchers, advanced mock) butuh adjust.

Time: 30-60 menit untuk simple suite, 2-4 jam untuk complex.

Common pain point

Mocking external module

Jest: jest.mock('./module', () => ({ ... })). Powerful but complex.

Vitest: vi.mock('./module', () => ({ ... })). Similar to Jest.

Bun test: mock.module('./module', () => ({ ... })). Newer API, occasional bug.

Untuk complex mocking: Vitest lebih mature dari Bun test.

TypeScript path alias

Vitest read tsconfig automatically. Bun test sometimes butuh manual path setup di bunfig.toml.

CI integration

GitHub Actions:

# Vitest
- uses: actions/setup-node@v4
  with: { node-version: 22 }
- run: bun install && bun run test

# Bun test  
- uses: oven-sh/setup-bun@v2
- run: bun install && bun test

Both straightforward.

Decision matrix

Project type	Recommended
Bun runtime (Hono, Elysia)	Bun test
Node runtime (Express, NestJS)	Vitest
Vite/Astro project	Vitest
Legacy Jest project	Vitest (migrate) atau Jest (stay)
Performance-critical CI	Bun test

Konteks Indonesia

Untuk SMB Indonesia 2026:

• Most project saya pakai Bun runtime → Bun test default
• Untuk klien dengan team Node existing → Vitest (less migration friction)
• Jangan default Jest untuk project baru (legacy choice di 2026)

Yang surprising

Bun test cepat banget di CI. Saya migrate 1 project klien dari Vitest ke Bun test → CI time turun dari 4.2 menit ke 1.8 menit. Saving signifikan untuk team yang push 20+ PR per minggu.

Vitest watch mode under Vite HMR sangat smooth — test re-run dalam 100-300ms saat file change. Untuk TDD workflow, Vitest still excellent.

Verdict

Recommended:

• Bun test untuk Bun runtime project (default jika Anda commit ke Bun)
• Vitest untuk Node runtime atau Vite/Astro project

Skip:

• Jest untuk new project (legacy choice)

Pilih based on runtime + ecosystem fit. Migration cost rendah, jadi tidak perlu over-think.