Agent skill

Testing

How to write and run fast, deterministic, behavior-focused pytest tests that never touch real external systems.

MITAuto-check passedTesting & QA

Install Testing

skills CLI

$ npx skills add extra-org/extra --skill testing -a claude-code

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

GitHub CLI

$ gh skill install extra-org/extra 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/extra-org/extra.git skills-src && mkdir -p .claude/skills && cp -r skills-src/.claude/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/extra-org/extra/tree/main/.claude/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/extra-org/extra/tree/main/.claude/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 extra-org/extra --skill testing -a codex

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

GitHub CLI

$ gh skill install extra-org/extra 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/extra-org/extra.git skills-src && mkdir -p .agents/skills && cp -r skills-src/.claude/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/extra-org/extra/tree/main/.claude/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 extra-org/extra --skill testing -a cursor

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

GitHub CLI

$ gh skill install extra-org/extra 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/extra-org/extra.git skills-src && mkdir -p .cursor/skills && cp -r skills-src/.claude/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/extra-org/extra/tree/main/.claude/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/extra-org/extra.git --path .claude/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 extra-org/extra --skill testing -a gemini-cli

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

GitHub CLI

$ gh skill install extra-org/extra 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/extra-org/extra.git skills-src && mkdir -p .gemini/skills && cp -r skills-src/.claude/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/extra-org/extra/tree/main/.claude/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 extra-org/extra 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 extra-org/extra --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/extra-org/extra.git skills-src && mkdir -p .github/skills && cp -r skills-src/.claude/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/extra-org/extra/tree/main/.claude/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 extra-org/extra --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 extra-org/extra 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/extra-org/extra.git skills-src && mkdir -p .opencode/skills && cp -r skills-src/.claude/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/extra-org/extra/tree/main/.claude/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: 113
Token cost: ~1.2k tokens
SKILL.md length: 530 words
Files: 1
Skills in repo: 14
Repo updated: Sep 7, 2026
First seen: Oct 7, 2026
Licence: MIT

At a glance

How to write and run fast, deterministic, behavior-focused pytest tests that never touch real external systems.

Works in 6 steps: Pick the category (see below) for what… → Arrange with fixtures for repeated setup… → Mock external boundaries… → …
Changing behavior
SKILL.md covers Purpose, When to Use This Skill, Files to Read First and Core Principles, plus 6 more sections
Calls make

What it does

Testing is an agent skill from extra-org/extra. How to write and run fast, deterministic, behavior-focused pytest tests that never touch real external systems. Use whenever adding or changing behavior, or fixing a bug.

Its SKILL.md is about 1.2k 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, covering Unit testing. It works with pytest. The repository describes itself as: Turn your product into an AI-powered assistant. The licence is MIT.

When your agent uses it

Changing behavior
Tasks that involve Unit testing

Example prompts

“/testing”

Requirements

Python 3

Workflow steps

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

Pick the category (see below) for what you are testing.
Arrange with fixtures for repeated setup (specs, compiled graphs, fake
Mock external boundaries (LLM/MCP/DB/HTTP) at the adapter seam, not deep
Write behavior assertions: given input, assert observable output/effects.
Cover negatives and security: invalid YAML/validation errors, missing
Run make test (and make check for the full gate). Fix failures.

What it can do on your machine

Read from SKILL.md and the folder at commit 023b0a0. 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:
- make
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 1.2k tokens when it runs. Until then it costs about 45 tokens; SKILL.md has 530 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it: ~45
When it runs · the whole SKILL.md, loaded when a task matches: ~1.2k

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

The full file from extra-org/extra at commit 023b0a0, republished under its MIT licence (© extra-org). 530 words, ~1,249 tokens.

Download SKILL.mdSave it as .claude/skills/testing/SKILL.md (or your agent's skills folder).

name: testing
description: How to write and run fast, deterministic, behavior-focused pytest tests that never touch real external systems. Use whenever adding or changing behavior, or fixing a bug.
generated: true
source: .ai/skills/testing.md

<!--
This file is generated by tools/skills.
Do not edit this file directly.
Edit .ai/skills/testing.md and run `make generate-ai`.
-->

Skill: Testing

Purpose

Define how to write and run tests for this Python project so that every meaningful behavior is covered by fast, deterministic, behavior-focused tests that never touch real external systems.

When to Use This Skill

Adding or changing any behavior (tests accompany behavior — almost always).
Fixing a bug (add a regression test first).
Working on the test suite or quality gate (task 0012).
Reviewing whether a change is adequately tested.

Files to Read First

AGENTS.md
docs/DEVELOPMENT_WORKFLOW.md
pyproject.toml ([tool.pytest.ini_options])
The skill for the area under test (runtime, prompts, plugins, tools, etc.).

Core Principles

Use pytest. Tests live under tests/, mirroring src/agentplatform/.
Test behavior through public interfaces, not private implementation details (test internals only when there is no public seam).
No real external systems in unit tests: never call real LLMs, real MCP servers, real databases, or third-party APIs. Mock/fake them.
Integration tests only when explicitly requested, and still without real secrets or live third-party calls — use fakes/local stand-ins.
Deterministic: control time, randomness, and ordering.
Regression tests for bugs: every fixed bug gets a test that fails before the fix.

Process

Pick the category (see below) for what you are testing.
Arrange with fixtures for repeated setup (specs, compiled graphs, fake resolver/access plugins, fake tools). Use @pytest.mark.parametrize for input variations.
Mock external boundaries (LLM/MCP/DB/HTTP) at the adapter seam, not deep inside.
Write behavior assertions: given input, assert observable output/effects.
Cover negatives and security: invalid YAML/validation errors, missing required prompt variables, denied protected-node access, plugin errors.
Run make test (and make check for the full gate). Fix failures.

Testing categories (use the right one)

Unit tests — a single function/class via its public interface.
Integration tests — multiple layers together (e.g. validate → compile → run) with fakes; only when requested.
Contract tests — verify plugin contracts and the YAML schema match docs/; catch drift early.
Golden example tests — a known YAML config produces a known compiled graph / rendered prompt; update goldens deliberately.
Negative tests — invalid specs, missing variables, denied access must fail clearly with the right error.
Security tests — protected access fail-closed, secrets redacted, no request-state leakage.

Show full SKILL.md (182 more words)Show less

Example pytest structure (illustrative, not product tests)

python

import pytest

@pytest.fixture
def valid_spec_dict() -> dict:
    return {"version": "1.0", "app": {"name": "demo"}, "...": "..."}

@pytest.mark.parametrize("missing_key", ["version", "app", "runtime"])
def test_validation_reports_missing_top_level_key(valid_spec_dict, missing_key):
    data = dict(valid_spec_dict)
    del data[missing_key]
    result = validate_spec(data)            # public interface
    assert not result.ok
    assert any(missing_key in e.message for e in result.errors)

Do not implement real product tests in this task. Only trivial repository smoke tests (e.g. import + version) belong here until task 0001+ create code.

Checklist Before Finishing

New/changed behavior has tests; bugs have regression tests.
Tests target public interfaces and assert behavior, not internals.
External systems are mocked/faked; no real LLM/MCP/DB/API calls.
Negative and security cases covered where relevant.
Tests are deterministic (time/randomness/order controlled).
Fixtures/parametrization used to keep tests readable and DRY.
make test (and make check) pass, or you state why they can't run.

Common Mistakes to Avoid

Calling real LLMs/MCP/DBs/APIs in unit tests.
Asserting on private attributes/log strings instead of behavior.
Flaky tests depending on real time, randomness, or ordering.
Over-mocking until the test asserts nothing meaningful.
Skipping negative/security tests because the happy path passes.
Committing secrets or production endpoints in fixtures.

Expected Final Report

State: which test files/categories were added or changed; what behaviors and edge/negative/security cases are now covered; mocks/fakes used for external boundaries; the result of make test / make check; and any coverage gaps intentionally left for a later task.

Files

Just SKILL.md in .claude/skills/testing of extra-org/extra.

Open the folder on GitHubat commit 023b0a0

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 skillextra-org/extra	113	—	~1.2k	Automated safety check: Pass	MIT	1 mo ago
Adk Verify Snippetsgoogle/adk-python	22k	—	~1.4k	Automated safety check: Pass	Apache-2.0	today
Hermetic Python Unit TestsdimensionalOS/dimos	4.6k	—	~1.4k	Automated safety check: Pass	Custom licence	today
Test GuardamElnagdy/guard-skills	1.3k	2 repos	~2.1k	Automated safety check: Pass	MIT	3 mo ago
Fla Optimization Loopfla-org/flash-linear-attention	5.8k	—	~2.6k	Automated safety check: Pass	MIT	yesterday
Pytest Runnersaleor/saleor	23k	—	~251	Automated safety check: Pass	BSD-3-Clause	yesterday

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Questions about Testing

What does Testing do?

How to write and run fast, deterministic, behavior-focused pytest tests that never touch real external systems. Testing is an agent skill from extra-org/extra. How to write and run fast, deterministic, behavior-focused pytest tests that never touch real external systems.

When should I use Testing?

Testing fits situations like: changing behavior; tasks that involve Unit testing.

How do I install Testing in Claude Code?

Run `npx skills add extra-org/extra --skill testing -a claude-code`. Or copy the skill folder (.claude/skills/testing in extra-org/extra) 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 extra-org/extra --skill testing -a codex`. Or copy the skill folder (.claude/skills/testing in extra-org/extra) 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 extra-org/extra --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 (make). Our summary lists: Python 3.

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 is published under the MIT licence (the repository's licence). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Testing use?

About 1.2k tokens (SKILL.md is roughly 5k 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: Adk Verify Snippets (google/adk-python, 22k stars), Hermetic Python Unit Tests (dimensionalOS/dimos, 4.6k stars), Test Guard (amElnagdy/guard-skills, 1.3k stars) and Fla Optimization Loop (fla-org/flash-linear-attention, 5.8k stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Testing?

extra-org (a GitHub organization) maintains it in extra-org/extra, which has 113 GitHub stars. The repository holds 14 skills in this directory. The repository was last updated on September 7, 2026.

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

Install Testing

Facts

At a glance

What it does

When your agent uses it

Example prompts

Requirements

Workflow steps

What it can do on your machine

Tool permissions

Runs code

Network

Credentials

Context cost

Safety

SKILL.md

Skill: Testing

Purpose

When to Use This Skill

Files to Read First

Core Principles

Process

Testing categories (use the right one)

Example pytest structure (illustrative, not product tests)

Checklist Before Finishing

Common Mistakes to Avoid

Expected Final Report

Files

Compare with similar skills

Similar skills

More from extra-org/extra

Related

Questions about Testing