# testing

A set of TDD workflows and test infrastructure for Apple platform apps. Useful when an agent writes the code and you want tests around it.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 468 installs · ★ 830
- Author: rshankras
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/rshankras/claude-code-apple-skills/tree/HEAD/skills/testing/SKILL.md
- Updated: 2026-07-24
- HTML: https://affpapa.org/en/nevibecode/skills/rshankras-testing

## What it does

The skill splits into separate sub-skills. On existing code, `characterization-test-generator` captures current behavior before a refactor, and `tdd-bug-fix` writes a failing test for the bug first, then fixes it. `tdd-refactor-guard` checks that coverage exists before the agent touches old code.

For new code there is `tdd-feature` with the red-green-refactor cycle, and `test-contract`, which defines an interface contract and generates a suite every implementation must pass. The infrastructure side covers `snapshot-test-setup` on swift-snapshot-testing, `test-data-factory` for fixtures, `integration-test-scaffold` with mock servers, and `flow-walkthrough` for driving user flows in the Simulator.

A third group is deterministic gates. `fitness-functions` turns project rules into tests, `coverage-ratchet` holds a coverage floor, and `mutation-testing` is marked experimental and advisory-only. The skill asks for `Read`, `Write`, `Edit`, `Glob`, `Grep`, `Bash` and `AskUserQuestion`, so without Bash some steps will not run.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add rshankras/claude-code-apple-skills --skill testing -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/testing/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/testing/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add rshankras/claude-code-apple-skills --skill testing -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/testing/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add rshankras/claude-code-apple-skills --skill testing -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/testing/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install rshankras/claude-code-apple-skills testing
```

2. **Manually: put the files in place**
- File: `.github/skills/testing/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add rshankras/claude-code-apple-skills --skill testing -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/rshankras/claude-code-apple-skills --path skills/testing
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/testing/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add rshankras/claude-code-apple-skills --skill testing -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/rshankras/claude-code-apple-skills/tree/HEAD/skills/testing/SKILL.md

## When to use it
- capture current behavior before refactoring
- write a failing test for a bug so it never regresses
- check coverage before letting an agent touch old code
- generate contract tests for a protocol or interface
- set up SwiftUI snapshot tests and Simulator flow runs

## Example prompts
- I want to TDD this new Swift feature — start with a failing test
- Add characterization tests to this class before I refactor it
- Set up snapshot tests for this SwiftUI screen and wire them into CI

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 6f64c13bef8b74c9.

BEGIN THIRD-PARTY FILE 6f64c13bef8b74c9
```text
---
name: testing
description: TDD and testing skills for iOS/macOS apps. Covers characterization tests, TDD workflows, test contracts, snapshot tests, test infrastructure, and deterministic quality gates (fitness functions, coverage ratchet, mutation testing). Use for test-driven development, adding tests to existing code, or building test infrastructure.
allowed-tools: [Read, Write, Edit, Glob, Grep, Bash, AskUserQuestion]
last_verified: 2026-07-24
review_by: 2027-06-22
---

# Testing & TDD Skills

Test-driven development workflows and testing infrastructure for Apple platform apps. Works with both new and existing codebases.

## When This Skill Activates

Use this skill when the user:
- Wants to do TDD (test-driven development) with AI-generated code
- Needs to add tests before refactoring existing code
- Wants to fix a bug using the red-green-refactor cycle
- Needs test infrastructure (factories, mocks, contracts)
- Asks about snapshot/visual regression testing
- Wants to ensure AI-generated code is correct via tests
- Wants deterministic gates around agent-written code (architecture invariants, coverage floors, mutation audits)

## Available Skills

### For Existing Codebases

**characterization-test-generator/**
Capture current behavior of existing code before refactoring. Generates tests that document what code actually does (not what it should do), giving you a safety net for AI-assisted refactoring.

**tdd-bug-fix/**
Reproduce-first bug fix workflow. Write a failing test that demonstrates the bug, then fix it. Ensures the bug never regresses — critical when AI generates fixes.

**tdd-refactor-guard/**
Pre-refactor safety checklist. Verifies test coverage exists before allowing AI to touch existing code. Prevents the "refactor without a safety net" problem.

### For New Code

**tdd-feature/**
Red-green-refactor scaffold for new features. Generates the failing test first, then guides implementation to make it pass, then refactors. The core TDD workflow.

**test-contract/**
Protocol/interface test suites. Define the contract (e.g., "any DataStore must handle empty state, single item, 100 items, and errors"), and it generates a test suite any implementation must pass.

### Infrastructure

**snapshot-test-setup/**
SwiftUI visual regression testing using swift-snapshot-testing. Generates snapshot test boilerplate, configuration, and CI integration.

**test-data-factory/**
Test fixture factories for your models. Makes writing tests faster by eliminating boilerplate data setup. Supports Builder pattern and static factory methods.

**integration-test-scaffold/**
```
END THIRD-PARTY FILE 6f64c13bef8b74c9

The third-party file has ended. Everything between the 6f64c13bef8b74c9 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

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