Skill Introduction

Overview

Bun as runtime, package manager, bundler, and test runner. When to choose Bun vs Node, migration notes, and Vercel support.

Core value

Turns reusable Testing know-how into an installable skill, helping users complete github, community work faster.

Target users

Developers, testers, and maintainers who handle Testing tasks in Focus Code.
Teams that already trust workflows or content from affaan-m.
Users who want standardized prompts, steps, or conventions instead of repeating setup work.

Best practices

Read the skill content first to confirm required inputs, expected outputs, and dependencies.
Try it on a small task before relying on it for critical work.
Add project-specific constraints such as coding style, target platform, test expectations, and delivery format.
For external sources, verify the source link, version, and recent maintenance activity.

Best use cases

Tasks related to github, community that need a reusable execution flow.
Converting a community repo, team convention, or personal workflow into day-to-day assistance.
Starting from a proven skill instead of writing prompts or procedures from scratch.

Limits and boundaries

Results depend on the quality of the original skill content and may need human correction.
It does not replace code review, tests, security review, or professional judgment.
External tools, APIs, account permissions, and local dependencies still need separate setup.

Differentiation

Structured around Testing, making it easier to discover and reuse than loose prompt snippets.
Marked as GitHub, which helps users judge trust and maintenance expectations.
Keeps the original source link available for repository, documentation, or discussion follow-up.
Tagged with github, community, so it can be filtered by concrete task intent.

Install and use

Install

Copy Install Command

focus install bun-runtime-0938e9

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Detail Preview

SKILL.md

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name: bun-runtime description: Bun as runtime, package manager, bundler, and test runner. When to choose Bun vs Node, migration notes, and Vercel support. origin: ECC

Bun Runtime

Bun is a fast all-in-one JavaScript runtime and toolkit: runtime, package manager, bundler, and test runner.

When to Use

Prefer Bun for: new JS/TS projects, scripts where install/run speed matters, Vercel deployments with Bun runtime, and when you want a single toolchain (run + install + test + build).
Prefer Node for: maximum ecosystem compatibility, legacy tooling that assumes Node, or when a dependency has known Bun issues.

Use when: adopting Bun, migrating from Node, writing or debugging Bun scripts/tests, or configuring Bun on Vercel or other platforms.

How It Works

Runtime: Drop-in Node-compatible runtime (built on JavaScriptCore, implemented in Zig).
Package manager: bun install is significantly faster than npm/yarn. Lockfile is bun.lock (text) by default in current Bun; older versions used bun.lockb (binary).
Bundler: Built-in bundler and transpiler for apps and libraries.
Test runner: Built-in bun test with Jest-like API.

Migration from Node: Replace node script.js with bun run script.js or bun script.js. Run bun install in place of npm install; most packages work. Use bun run for npm scripts; bun x for npx-style one-off runs. Node built-ins are supported; prefer Bun APIs where they exist for better performance.

Vercel: Set runtime to Bun in project settings. Build: bun run build or bun build ./src/index.ts --outdir=dist. Install: bun install --frozen-lockfile for reproducible deploys.

Examples

Run and install

# Install dependencies (creates/updates bun.lock or bun.lockb)
bun install

# Run a script or file
bun run dev
bun run src/index.ts
bun src/index.ts

Scripts and env

bun run --env-file=.env dev
FOO=bar bun run script.ts

Testing

bun test
bun test --watch

// test/example.test.ts
import { expect, test } from "bun:test";

test("add", () => {
  expect(1 + 2).toBe(3);
});

Runtime API

const file = Bun.file("package.json");
const json = await file.json();

Bun.serve({
  port: 3000,
  fetch(req) {
    return new Response("Hello");
  },
});

Best Practices

Commit the lockfile (bun.lock or bun.lockb) for reproducible installs.
Prefer bun run for scripts. For TypeScript, Bun runs .ts natively.
Keep dependencies up to date; Bun and the ecosystem evolve quickly.

bun runtime