Agent skill

Writing Good Tests

A skill your agent uses when writing or reviewing tests - covers test philosophy, condition-based waiting, mocking strategy, and test isolation

No licenceAuto-check passedTesting & QA

Install Writing Good Tests

skills CLI

$ npx skills add ed3dai/ed3d-plugins --skill writing-good-tests -a claude-code

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

GitHub CLI

$ gh skill install ed3dai/ed3d-plugins writing-good-tests --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/ed3dai/ed3d-plugins.git skills-src && mkdir -p .claude/skills && cp -r skills-src/plugins/ed3d-house-style/skills/writing-good-tests .claude/skills/writing-good-tests && 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 "writing-good-tests" agent skill from https://github.com/ed3dai/ed3d-plugins/tree/main/plugins/ed3d-house-style/skills/writing-good-tests into .claude/skills/writing-good-tests/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-good-tests", 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/ed3dai/ed3d-plugins/tree/main/plugins/ed3d-house-style/skills/writing-good-tests

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 ed3dai/ed3d-plugins --skill writing-good-tests -a codex

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

GitHub CLI

$ gh skill install ed3dai/ed3d-plugins writing-good-tests --agent codex

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

Manual copy

$ git clone --depth 1 https://github.com/ed3dai/ed3d-plugins.git skills-src && mkdir -p .agents/skills && cp -r skills-src/plugins/ed3d-house-style/skills/writing-good-tests .agents/skills/writing-good-tests && 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 "writing-good-tests" agent skill from https://github.com/ed3dai/ed3d-plugins/tree/main/plugins/ed3d-house-style/skills/writing-good-tests into .agents/skills/writing-good-tests/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-good-tests", 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 ed3dai/ed3d-plugins --skill writing-good-tests -a cursor

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

GitHub CLI

$ gh skill install ed3dai/ed3d-plugins writing-good-tests --agent cursor

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

Manual copy

$ git clone --depth 1 https://github.com/ed3dai/ed3d-plugins.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/plugins/ed3d-house-style/skills/writing-good-tests .cursor/skills/writing-good-tests && 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 "writing-good-tests" agent skill from https://github.com/ed3dai/ed3d-plugins/tree/main/plugins/ed3d-house-style/skills/writing-good-tests into .cursor/skills/writing-good-tests/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-good-tests", 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/ed3dai/ed3d-plugins.git --path plugins/ed3d-house-style/skills/writing-good-tests

--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 ed3dai/ed3d-plugins --skill writing-good-tests -a gemini-cli

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

GitHub CLI

$ gh skill install ed3dai/ed3d-plugins writing-good-tests --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/ed3dai/ed3d-plugins.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/plugins/ed3d-house-style/skills/writing-good-tests .gemini/skills/writing-good-tests && 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 "writing-good-tests" agent skill from https://github.com/ed3dai/ed3d-plugins/tree/main/plugins/ed3d-house-style/skills/writing-good-tests into .gemini/skills/writing-good-tests/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-good-tests", 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 ed3dai/ed3d-plugins writing-good-tests

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 ed3dai/ed3d-plugins --skill writing-good-tests -a github-copilot

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

Manual copy

$ git clone --depth 1 https://github.com/ed3dai/ed3d-plugins.git skills-src && mkdir -p .github/skills && cp -r skills-src/plugins/ed3d-house-style/skills/writing-good-tests .github/skills/writing-good-tests && 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 "writing-good-tests" agent skill from https://github.com/ed3dai/ed3d-plugins/tree/main/plugins/ed3d-house-style/skills/writing-good-tests into .github/skills/writing-good-tests/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-good-tests", 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 ed3dai/ed3d-plugins --skill writing-good-tests -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 ed3dai/ed3d-plugins writing-good-tests --agent opencode

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

Manual copy

$ git clone --depth 1 https://github.com/ed3dai/ed3d-plugins.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/plugins/ed3d-house-style/skills/writing-good-tests .opencode/skills/writing-good-tests && 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 "writing-good-tests" agent skill from https://github.com/ed3dai/ed3d-plugins/tree/main/plugins/ed3d-house-style/skills/writing-good-tests into .opencode/skills/writing-good-tests/ in this project. Copy the whole folder (SKILL.md and every file beside it), keep the folder name "writing-good-tests", 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: writing-good-tests
GitHub stars: 250
Used in: 1 other repo
Token cost: ~2.7k tokens
SKILL.md length: 830 words
Files: 1
Skills in repo: 34
Repo updated: Sep 6, 2026
First seen: Oct 7, 2026
Licence: None found

At a glance

A skill your agent uses when writing or reviewing tests - covers test philosophy, condition-based waiting, mocking strategy, and test isolation

Works in 5 steps: Test behavior, not implementation —… → Integration tests provide better… → Wait for actual conditions, not… → …
Reviewing tests - covers test philosophy
SKILL.md covers Philosophy, Test Structure, Condition-Based Waiting and Mocking Strategy, plus 5 more sections
Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Writing Good Tests is an agent skill from ed3dai/ed3d-plugins. Use when writing or reviewing tests - covers test philosophy, condition-based waiting, mocking strategy, and test isolation

Its SKILL.md is about 2.7k 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: Ed's repo of Claude Code plugins, centered around a research-plan-implement workflow. Only a tiny bit cursed. If you're lucky.

When your agent uses it

Reviewing tests - covers test philosophy
Condition-based waiting
Mocking strategy

Example prompts

“/writing-good-tests”

Workflow steps

5 steps, taken from the first numbered list in SKILL.md.

Test behavior, not implementation — refactoring shouldn't break tests
Integration tests provide better confidence-to-cost ratio than unit tests
Wait for actual conditions, not arbitrary timeouts
Mock strategically — real dependencies when feasible, mocks for external systems
Don't pollute production code with test-only methods

What it can do on your machine

Read from SKILL.md and the folder at commit 0c90f4b. 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
No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).
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

Writing Good Tests loads about 2.7k tokens when it runs. Until then it costs about 36 tokens; SKILL.md has 830 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~36
When it runs · the whole SKILL.md, loaded when a task matches: ~2.7k

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

Without a licence we can't republish the file, so here is its outline and opening line. It has 830 words (~2,675 tokens).

“"Write tests. Not too many. Mostly integration." — Kent C. Dodds”

— opening of SKILL.md by ed3dai

name: writing-good-tests
user-invocable: false

Outline of SKILL.md

Writing Good Tests
Philosophy
Test Structure
Condition-Based Waiting
Generic Polling Function
Quick Patterns
When Arbitrary Timeout IS Correct
Mocking Strategy
Don't Mock What You Don't Own
Managed vs Unmanaged Dependencies
Anti-Pattern: Testing Mock Behavior
Anti-Pattern: Mocking Without Understanding
Anti-Pattern: Incomplete Mocks
When Mocks Become Too Complex
Anti-Pattern: Test-Only Methods in Production
Test Isolation
What to Clean Up
What's OK to Leave
Preventing Order Dependencies
Quick Reference
Red Flags
TDD Connection
Property-Based Testing
When to Use PBT
When NOT to Use PBT
PBT Quality Gates

Read the full SKILL.md on GitHub

Files

Just SKILL.md in plugins/ed3d-house-style/skills/writing-good-tests of ed3dai/ed3d-plugins.

Open the folder on GitHubat commit 0c90f4b

Used in 1 other repository

We found 1 copy of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in ed3dai/ed3d-plugins, which our catalogue first saw on October 7, 2026.

mattiacerutti/supernova.agents/skills/writing-good-tests

Compare with similar skills

Writing Good Tests 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.

Writing Good Tests compared with similar skills
Skill	Stars	Used in	Tokens	Auto-check	Licence	Repo updated
Writing Good Tests this skilled3dai/ed3d-plugins	250	1 repos	~2.7k	Automated safety check: Pass	None	1 mo ago
Web Application Testinganthropics/skills	180k	51 repos	~966	Automated safety check: Pass	Apache-2.0	yesterday
Diagnosing Bugsfossasia/eventyay-interpretation	1.6k	32 repos	~2.1k	Automated safety check: Pass	Apache-2.0	4 days ago
TDDpietheinstrengholt/rssmonster	564	30 repos	~906	Automated safety check: Pass	MIT	2 days ago
TDD WorkflowhellangleZ/burn-in-cceverywhere-ralph	112	11 repos	~2.4k	Automated safety check: Pass	None	8 mo ago
TDDsanity-io/sanity	6.4k	20 repos	~1k	Automated safety check: Pass	MIT	yesterday

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Questions about Writing Good Tests

What does Writing Good Tests do?

A skill your agent uses when writing or reviewing tests - covers test philosophy, condition-based waiting, mocking strategy, and test isolation. Writing Good Tests is an agent skill from ed3dai/ed3d-plugins.

When should I use Writing Good Tests?

Writing Good Tests fits situations like: reviewing tests - covers test philosophy; condition-based waiting; mocking strategy.

How do I install Writing Good Tests in Claude Code?

Run `npx skills add ed3dai/ed3d-plugins --skill writing-good-tests -a claude-code`. Or copy the skill folder (plugins/ed3d-house-style/skills/writing-good-tests in ed3dai/ed3d-plugins) into .claude/skills/writing-good-tests in your project. Claude Code loads it when a task matches its description.

How do I install Writing Good Tests in Codex?

Run `npx skills add ed3dai/ed3d-plugins --skill writing-good-tests -a codex`. Or copy the skill folder (plugins/ed3d-house-style/skills/writing-good-tests in ed3dai/ed3d-plugins) into .agents/skills/writing-good-tests in your project. Codex loads it when a task matches its description.

Can I use Writing Good Tests 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 ed3dai/ed3d-plugins --skill writing-good-tests -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/writing-good-tests, .gemini/skills/writing-good-tests, .github/skills/writing-good-tests and .opencode/skills/writing-good-tests in your project.

What does Writing Good Tests need to run?

SKILL.md names no scripts, command-line tools or credentials: Writing Good Tests is instructions for the agent only.

Does Writing Good Tests 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 Writing Good Tests 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 Writing Good Tests use?

No licence was found for Writing Good Tests or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.

How many tokens does Writing Good Tests use?

About 2.7k tokens (SKILL.md is roughly 11k 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 Writing Good Tests?

Skills that share tags, products or a category with Writing Good Tests: Web Application Testing (anthropics/skills, 180k stars), Diagnosing Bugs (fossasia/eventyay-interpretation, 1.6k stars), TDD (pietheinstrengholt/rssmonster, 564 stars) and TDD Workflow (hellangleZ/burn-in-cceverywhere-ralph, 112 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Writing Good Tests?

ed3dai (a GitHub organization) maintains it in ed3dai/ed3d-plugins, which has 250 GitHub stars. The repository holds 34 skills in this directory. The repository was last updated on September 6, 2026.

Source: ed3dai/ed3d-plugins on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.

Install Writing Good Tests

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

Used in 1 other repository

Compare with similar skills

Similar skills

More from ed3dai/ed3d-plugins

Related

Questions about Writing Good Tests