Agent skill

Testing

UI testing mode, accessibility identifiers, and testing workflows.

Custom licenceAuto-check passedTesting & QA

Install Testing

skills CLI

$ npx skills add ad-repo/nullplayer --skill testing -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI

$ gh skill install ad-repo/nullplayer testing --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy

$ git clone --depth 1 https://github.com/ad-repo/nullplayer.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/testing .claude/skills/testing && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Paste into Claude Code

Install the "testing" agent skill from https://github.com/ad-repo/nullplayer/tree/main/skills/testing into .claude/skills/testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing", then confirm the skill loads.

Claude Code copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

$skill-installer

$skill-installer install https://github.com/ad-repo/nullplayer/tree/main/skills/testing

Type this inside Codex. $skill-installer <name> installs a curated skill from openai/skills. The installer writes to $CODEX_HOME/skills (default ~/.codex/skills). Restart Codex if the skill does not show up.

skills CLI

$ npx skills add ad-repo/nullplayer --skill testing -a codex

Project install goes to .agents/skills/; add -g for ~/.codex/skills/.

GitHub CLI

$ gh skill install ad-repo/nullplayer testing --agent codex

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/ad-repo/nullplayer.git skills-src && mkdir -p .agents/skills && cp -r skills-src/skills/testing .agents/skills/testing && rm -rf skills-src

Use ~/.agents/skills/ instead of .agents/skills for a personal install.

Codex skills documentation · loads skills from .agents/skills/

Paste into Codex

Install the "testing" agent skill from https://github.com/ad-repo/nullplayer/tree/main/skills/testing into .agents/skills/testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing", then confirm the skill loads.

Codex copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add ad-repo/nullplayer --skill testing -a cursor

Project install goes to .agents/skills/; add -g for ~/.cursor/skills/.

GitHub CLI

$ gh skill install ad-repo/nullplayer testing --agent cursor

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/ad-repo/nullplayer.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/skills/testing .cursor/skills/testing && rm -rf skills-src

Use ~/.cursor/skills/ instead of .cursor/skills for a personal install.

Cursor skills documentation · loads skills from .cursor/skills/, .agents/skills/, .claude/skills/, .codex/skills/

Paste into Cursor

Install the "testing" agent skill from https://github.com/ad-repo/nullplayer/tree/main/skills/testing into .cursor/skills/testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing", then confirm the skill loads.

Cursor copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

gemini skills install

$ gemini skills install https://github.com/ad-repo/nullplayer.git --path skills/testing

--scope user (default) or --scope workspace; --path is the subfolder of the repo that holds the skill; --consent skips the security confirmation prompt.

skills CLI

$ npx skills add ad-repo/nullplayer --skill testing -a gemini-cli

Project install goes to .agents/skills/; add -g for ~/.gemini/skills/.

GitHub CLI

$ gh skill install ad-repo/nullplayer testing --agent gemini-cli

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/ad-repo/nullplayer.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/skills/testing .gemini/skills/testing && rm -rf skills-src

Use ~/.gemini/skills/ instead of .gemini/skills for a personal install, then run /skills reload.

Gemini CLI skills documentation · loads skills from .gemini/skills/, .agents/skills/

Paste into Gemini CLI

Install the "testing" agent skill from https://github.com/ad-repo/nullplayer/tree/main/skills/testing into .gemini/skills/testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing", then confirm the skill loads.

Gemini CLI copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

GitHub CLI

$ gh skill install ad-repo/nullplayer testing

Installs for Copilot at project scope by default; add --scope user for a personal install. Preview a skill first with gh skill preview. Needs GitHub CLI 2.90.0 or later (public preview).

skills CLI

$ npx skills add ad-repo/nullplayer --skill testing -a github-copilot

Project install goes to .agents/skills/; add -g for ~/.copilot/skills/.

Manual copy

$ git clone --depth 1 https://github.com/ad-repo/nullplayer.git skills-src && mkdir -p .github/skills && cp -r skills-src/skills/testing .github/skills/testing && rm -rf skills-src

Use ~/.copilot/skills/ instead of .github/skills for a personal install. Commit .github/skills so cloud agent and code review can use it.

GitHub Copilot skills documentation · loads skills from .github/skills/, .claude/skills/, .agents/skills/

Paste into GitHub Copilot

Install the "testing" agent skill from https://github.com/ad-repo/nullplayer/tree/main/skills/testing into .github/skills/testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing", then confirm the skill loads.

GitHub Copilot copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

skills CLI

$ npx skills add ad-repo/nullplayer --skill testing -a opencode

OpenCode documents no install command of its own. Project install goes to .agents/skills/; add -g for ~/.config/opencode/skills/.

GitHub CLI

$ gh skill install ad-repo/nullplayer testing --agent opencode

Project scope by default (.agents/skills/); add --scope user for a personal install.

Manual copy

$ git clone --depth 1 https://github.com/ad-repo/nullplayer.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/skills/testing .opencode/skills/testing && rm -rf skills-src

Use ~/.config/opencode/skills/ instead of .opencode/skills for a personal install.

OpenCode skills documentation · loads skills from .opencode/skills/, .claude/skills/, .agents/skills/

Paste into OpenCode

Install the "testing" agent skill from https://github.com/ad-repo/nullplayer/tree/main/skills/testing into .opencode/skills/testing/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "testing", then confirm the skill loads.

OpenCode copies the folder itself, the same result as the manual copy. Check what it changed before you commit it.

Facts

Skill name: testing
GitHub stars: 157
Token cost: ~5.3k tokens
SKILL.md length: 2,258 words
Files: 1
Skills in repo: 39
Repo updated: Oct 8, 2026
First seen: Oct 7, 2026
Licence: Custom licence

At a glance

UI testing mode, accessibility identifiers, and testing workflows.

Works in 5 steps: Never Modify Code to Pass Tests → Never Dumb Down Tests → Quality Over Quantity → …
Adding testable UI elements
SKILL.md covers Quick Start, Core Principles, Test Structure and Window geometry: measure it,…, plus 7 more sections
Calls swift, xcodebuild and osascript

What it does

Testing is an agent skill from ad-repo/nullplayer. UI testing mode, accessibility identifiers, and testing workflows. Use when writing tests, adding testable UI elements, or understanding test structure and philosophy.

Its SKILL.md is about 5.3k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Testing & QA. The repository describes itself as: nullPlayer is a free open source macOS media player with some unique features.

When your agent uses it

Adding testable UI elements
Understanding test structure and philosophy

Example prompts

“/testing”

Workflow steps

5 steps, taken from the step headings in SKILL.md.

Never Modify Code to Pass Tests
Never Dumb Down Tests
Quality Over Quantity
Target 95% Code Coverage
End-to-End Tests Must Be Realistic

What it can do on your machine

Read from SKILL.md and the folder at commit 9281472. It shows what the files ask for, not the result of running them.

Tool permissions
Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.
From allowed-tools in the SKILL.md frontmatter.
Runs code
Shell commands in SKILL.md call:
- swift
- xcodebuild
- osascript
- xcrun
From the folder's file list and the shell code blocks in SKILL.md.
Network
No URLs in SKILL.md.
From URLs in SKILL.md, links to its own repository left out.
Credentials
Names no API keys, tokens, secrets or passwords.
From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Testing loads about 5.3k tokens when it runs. Until then it costs about 44 tokens; SKILL.md has 2,258 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~44
When it runs · the whole SKILL.md, loaded when a task matches: ~5.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

Its licence (Custom licence) doesn't allow us to republish the file, so here is its outline and opening line. It has 2,258 words (~5,262 tokens).

“This document defines the testing philosophy, standards, and practices for NullPlayer.”

— opening of SKILL.md by ad-repo, Custom licence

name: testing

Outline of SKILL.md

Testing Guide
Quick Start
Core Principles
1. Never Modify Code to Pass Tests
2. Never Dumb Down Tests
3. Quality Over Quantity
4. Target 95% Code Coverage
5. End-to-End Tests Must Be Realistic
Test Structure
Unit Test Coverage
Window geometry: measure it, never reason about it
The loop
What to instrument
Unit-test the pure part
Profiling: measure the build the user runs
The metric that works across builds
Five ways a profile lies
Compare identical state, or do not compare
UI Tests
UI Testing Mode
Launching into a given skin or state — see app-control
Running Tests
Local Development
Local Library Regression Checklist
Video and Casting Regression Checklist
Writing Good Tests
Test Structure
Naming Conventions
Assertions
Handling Async Operations

Read the full SKILL.md on GitHub

Files

Just SKILL.md in skills/testing of ad-repo/nullplayer.

Open the folder on GitHubat commit 9281472

Compare with similar skills

Testing next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Testing compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Testing this skillad-repo/nullplayer	157	—	~5.3k	Automated safety check: Pass	Custom licence	today
Web Application Testinganthropics/skills	180k	51 repos	~966	Automated safety check: Pass	Apache-2.0	3 days ago
Before and After Screenshotsmichaelshimeles/skills	1.3k	2 repos	~1k	Automated safety check: Pass	MIT	4 days ago
Testing OpenLogi UIAprilNEA/OpenLogi	23k	—	~1.1k	Automated safety check: Pass	Apache-2.0	5 days ago
Reproduce Chat Statesdifferent-ai/openwork	24k	—	~673	Automated safety check: Pass	Custom licence	today
Chrome Tracelayoutit/polycss	759	—	~2k	Automated safety check: Pass	MIT	1 mo ago

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Web Application Testing
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Testing & QAAuto-check passed
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Testing OpenLogi UI
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Testing & QAAuto-check: notes

Questions about Testing

What does Testing do?

UI testing mode, accessibility identifiers, and testing workflows. Testing is an agent skill from ad-repo/nullplayer. UI testing mode, accessibility identifiers, and testing workflows.

When should I use Testing?

Testing fits situations like: adding testable UI elements; understanding test structure and philosophy.

How do I install Testing in Claude Code?

Run `npx skills add ad-repo/nullplayer --skill testing -a claude-code`. Or copy the skill folder (skills/testing in ad-repo/nullplayer) into .claude/skills/testing in your project. Claude Code loads it when a task matches its description.

How do I install Testing in Codex?

Run `npx skills add ad-repo/nullplayer --skill testing -a codex`. Or copy the skill folder (skills/testing in ad-repo/nullplayer) into .agents/skills/testing in your project. Codex loads it when a task matches its description.

Can I use Testing in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add ad-repo/nullplayer --skill testing -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/testing, .gemini/skills/testing, .github/skills/testing and .opencode/skills/testing in your project.

What does Testing need to run?

Going by SKILL.md and its folder, Testing needs the command-line tools its instructions call (swift, xcodebuild, osascript and xcrun).

Does Testing access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Testing safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Testing use?

Testing has a licence file (the repository's licence) that doesn't match a standard licence. Read it on GitHub before reusing the skill.

How many tokens does Testing use?

About 5.3k tokens (SKILL.md is roughly 21k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Testing?

Skills that share tags, products or a category with Testing: Web Application Testing (anthropics/skills, 180k stars), Before and After Screenshots (michaelshimeles/skills, 1.3k stars), Testing OpenLogi UI (AprilNEA/OpenLogi, 23k stars) and Reproduce Chat States (different-ai/openwork, 24k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Testing?

ad-repo (a GitHub user) maintains it in ad-repo/nullplayer, which has 157 GitHub stars. The repository holds 39 skills in this directory. The repository was last updated on October 8, 2026.

Source: ad-repo/nullplayer on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Testing

Install Testing

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Files

Compare with similar skills

Similar skills

Web Application Testing

Before and After Screenshots

Testing OpenLogi UI

Reproduce Chat States

Chrome Trace

Auto GitHub Contributor

More from ad-repo/nullplayer

Skin Screenshots

Vis Classic Guide

App Control

Chromecast Casting

Emby Integration

Live UI Testing

Questions about Testing

Install Testing

Facts

At a glance

What it does

When your agent uses it

Example prompts

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Files

Compare with similar skills

Similar skills

More from ad-repo/nullplayer

Related

Questions about Testing