live-codes/livecodes is a browser-based code playground for writing and running code in more than 90 languages, frameworks, and processors. It is used to experiment with code, import modules, embed interactive editors in websites, and host playgrounds on a static file server without a backend. The catalogue add-ons support working with LiveCodes.
Borrowing it
Nothing to install: this file belongs to live-codes/livecodes. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.
curl -O https://raw.githubusercontent.com/live-codes/livecodes/develop/.agents/skills/livecodes/testing/SKILL.mdgit clone --depth 1 https://github.com/live-codes/livecodesWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/live-codes/livecodes/testing)<a href="https://agentmods.dev/skills/live-codes/livecodes/testing"><img src="https://agentmods.dev/badge/skills/live-codes/livecodes/testing/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/live-codes/livecodes/testing"><img src="https://agentmods.dev/badge/skills/live-codes/livecodes/testing.svg" alt="Reviewed on agentmods" width="80" height="20"></a>- NVIDIA SkillSpector pass
What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00047 | $0.01834 |
| Opus 5.5 | $0.00019 | $0.00734 |
| Sonnet 5.5 | $0.00009 | $0.00367 |
| Haiku 4.5 | $0.00005 | $0.00183 |
Grade A, and why
testing scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 1mo ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
How it starts
The opening of the file, as written. The whole thing — 308 lines — stays where its author put it; the contents beside it link to each section on GitHub.
LiveCodes — Write and Run Tests
LiveCodes includes Jest and Testing Library for automated testing in the browser. Tests run against the result page in real-time.
Setup
import { createPlayground } from 'livecodes';
// Project with tests
createPlayground('#container', {
template: 'jest', // Jest starter template
params: { tests: 'open' }, // Show tests panel
});
// Custom test configuration
createPlayground('#container', {
config: {
activeEditor: 'script',
script: {
language: 'javascript',
content: `
export function add(a, b) {
return a + b;
}
export function greet(name) {
return 'Hello, ' + name;
}
`,
},
tests: {
language: 'javascript',
content: `
import { add, greet } from './script';
describe('add', () => {
test('adds numbers', () => {
expect(add(1, 2)).toBe(3);
});
test('handles negatives', () => {
expect(add(-1, -2)).toBe(-3);
});
});
describe('greet', () => {
test('greets by name', () => {
expect(greet('World')).toBe('Hello, World');
});
});
`,
},
},
params: { tests: 'open' },
});
Core Patterns
Test exports from script editor
// Script editor (script.js)
export default function greet(name) {
return 'Hello, ' + name;
}
export const add = (a, b) => a + b;
// Also available in global scope
window.multiply = (a, b) => a * b;
// Tests editor
import greet, { add } from './script'; // Relative import, no extension
describe('imports', () => {
test('greet', () => {
expect(greet('World')).toBe('Hello, World');
});
test('add', () => {
expect(add(1, 2)).toBe(3);
});
});
describe('globals', () => {
test('multiply', () => {
expect(window.multiply(2, 3)).toBe(6);
});
});
Use Testing Library
// React Testing Library
import { render, screen, fireEvent } from '@testing-library/react';
import '@testing-library/jest-dom';
import userEvent from '@testing-library/user-event';
test('button click', async () => {
render(<MyComponent />);
await userEvent.click(screen.getByText('Click me'));
expect(screen.getByText('Clicked')).toBeInTheDocument();
});
// DOM Testing Library
import { getByText, waitFor } from '@testing-library/dom';
test('element appears', async () => {
document.body.innerHTML = '<div id="root"></div>';
// ... render something
await waitFor(() => {
expect(getByText(document.body, 'Loaded')).toBeTruthy();
});
});
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 1mo ago Changed · +1 lines · -2 tokens per session b98d4f958fdb
- 2mo ago First seen · 307 lines · 49 tokens per session scan A 979cdcd3b692
testing is a skill published in the GitHub repository live-codes/livecodes (1,525 stars, last pushed 13d ago), licensed MIT. It adds 47 tokens to every session and 1,834 once invoked, about $0.0002 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.
testing compared with skills from other repositories
| Mod | Type | Stars | Last push | Licence | Scan | Tokens | Works with |
|---|---|---|---|---|---|---|---|
| testinglive-codes/livecodes | Skill | 1.5k | 13d ago | MIT | A | 47 | Claude Code, Codex |
| test-electron-appPostHog/posthog | Skill | 41k | yesterday | none | A | 112 | Claude Code |
| running-mobile-demo-flowsPostHog/posthog | Skill | 41k | yesterday | none | A | 103 | Claude Code, Codex |
| handle-regressionloopdive/js2 | Skill | 67 | today | Apache-2.0 | A | 32 | Claude Code |
| playwright-e2e-testingJPeetz/agent-skills | Skill | 15 | 9d ago | none | A | 213 | Claude Code, Codex |
| insta-snapshotsoxc-project/oxc | Skill | 23k | today | MIT | A | 25 | Claude Code, Codex |
| ux-acceptance-testeremdash-cms/emdash | Skill | 14k | today | MIT | A | 46 | Claude Code, Codex |