How do I install the Testing Mastery skill?

Run npx skillmds@latest add tomevault-io/testing-mastery in your terminal (requires Node.js), paste this page's agent-chat prompt into Claude, Cursor, or any MCP-connected agent, or download the SKILL.md file and copy it into your agent's skills directory.

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Is Testing Mastery free to use?

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Who published Testing Mastery?

tomevault-io (@tomevault-io) published this skill. Their other Agent Skills are listed on their SkillMD profile.

Testing Mastery by tomevault-io — Agent Skill

Name: Testing Mastery
Author: tomevault-io

File contents

Testing Mastery — Unified Testing Skill

Write tests that document intent, catch regressions, and run fast. Choose the right strategy for the right situation.

Decision Tree: Which Testing Strategy?

Is this a new feature?
├─ YES → Use TDD (see references/tdd-cycle.md)
│        Write failing test → Minimal code → Refactor
└─ NO
   ├─ Is this a bug fix?
   │  └─ YES → Write regression test first, then fix
   ├─ Is this a critical user flow (login, checkout)?
   │  └─ YES → E2E test (see references/e2e-playwright.md)
   └─ Is this business logic / data transformation?
      └─ YES → Unit + Integration tests (see references/unit-integration.md)

Testing Pyramid

        /\          E2E (Few, ~10%)
       /  \         Critical user flows only
      /----\
     /      \       Integration (Some, ~20%)
    /--------\      API, DB, service contracts
   /          \
  /------------\    Unit (Many, ~70%)
                    Functions, classes, utilities

Core Principles

Principle	Rule
AAA	Arrange → Act → Assert
Fast	Unit < 100ms, Integration < 1s
Isolated	No test depends on another
Behavior	Test WHAT, not HOW
Minimal	One assertion per test (ideally)

Quick Reference

I need to...	Use	Reference
Build feature test-first	TDD (RED-GREEN-REFACTOR)	tdd-cycle.md
Write unit/integration tests	Mocking, data strategies, patterns	unit-integration.md
Test critical user flows in browser	E2E with Playwright	e2e-playwright.md

Anti-Patterns (Universal)

❌ Don't	✅ Do
Test implementation details	Test observable behavior
Write tests after shipping	Write tests before/during
Duplicate test code	Use factories & fixtures
Complex test setup	Simplify or split
Ignore flaky tests	Fix root cause
Skip cleanup	Reset state in teardown
Multiple asserts per test	One behavior per test

🔧 Runtime Scripts

Script	Purpose	Command
`scripts/test_runner.py`	Unified test execution	`python scripts/test_runner.py <project_path>`
`scripts/playwright_runner.py`	Browser E2E testing	`python scripts/playwright_runner.py <url>`
	With screenshot	`python scripts/playwright_runner.py <url> --screenshot`
	Accessibility check	`python scripts/playwright_runner.py <url> --a11y`

Remember: The test is the specification. If you can't write a test for it, you don't understand the requirement.

Converted and distributed by TomeVault — claim your Tome and manage your conversions.

---name: testing-masterydescription: Unified testing skill — TDD workflow, unit/integration patterns, E2E/Playwright strategies. Replaces tdd-workflow + testing-patterns + webapp-testing. Use when this capability is needed.---# Testing Mastery — Unified Testing Skill> Write tests that **document intent**, catch regressions, and run fast. Choose the right strategy for the right situation.---## Decision Tree: Which Testing Strategy?```Is this a new feature?├─ YES → Use TDD (see references/tdd-cycle.md)│ Write failing test → Minimal code → Refactor└─ NO ├─ Is this a bug fix? │ └─ YES → Write regression test first, then fix ├─ Is this a critical user flow (login, checkout)? │ └─ YES → E2E test (see references/e2e-playwright.md) └─ Is this business logic / data transformation? └─ YES → Unit + Integration tests (see references/unit-integration.md)```---## Testing Pyramid``` /\ E2E (Few, ~10%) / \ Critical user flows only /----\ / \ Integration (Some, ~20%) /--------\ API, DB, service contracts / \ /------------\ Unit (Many, ~70%) Functions, classes, utilities```---## Core Principles| Principle | Rule ||-----------|------|| **AAA** | Arrange → Act → Assert || **Fast** | Unit < 100ms, Integration < 1s || **Isolated** | No test depends on another || **Behavior** | Test WHAT, not HOW || **Minimal** | One assertion per test (ideally) |---## Quick Reference| I need to... | Use | Reference ||--------------|-----|-----------|| Build feature test-first | TDD (RED-GREEN-REFACTOR) | [tdd-cycle.md](references/tdd-cycle.md) || Write unit/integration tests | Mocking, data strategies, patterns | [unit-integration.md](references/unit-integration.md) || Test critical user flows in browser | E2E with Playwright | [e2e-playwright.md](references/e2e-playwright.md) |---## Anti-Patterns (Universal)| ❌ Don't | ✅ Do ||----------|-------|| Test implementation details | Test observable behavior || Write tests after shipping | Write tests before/during || Duplicate test code | Use factories & fixtures || Complex test setup | Simplify or split || Ignore flaky tests | Fix root cause || Skip cleanup | Reset state in teardown || Multiple asserts per test | One behavior per test |---## 🔧 Runtime Scripts| Script | Purpose | Command ||--------|---------|---------|| `scripts/test_runner.py` | Unified test execution | `python scripts/test_runner.py <project_path>` || `scripts/playwright_runner.py` | Browser E2E testing | `python scripts/playwright_runner.py <url>` || | With screenshot | `python scripts/playwright_runner.py <url> --screenshot` || | Accessibility check | `python scripts/playwright_runner.py <url> --a11y` |---> **Remember:** The test is the specification. If you can't write a test for it, you don't understand the requirement.---> Converted and distributed by [TomeVault](https://tomevault.io/claim/tai-ch0802) — claim your Tome and manage your conversions.

Frequently asked questions

Testing Mastery