33-js-concepts: Skill for Claude Code

Skill: Test Writer for Concept Pages

Use this skill to generate comprehensive Vitest tests for all code examples in a concept documentation page. Tests verify that code examples in the documentation are accurate and work as described.

When to Use

• After writing a new concept page
• When adding new code examples to existing pages
• When updating existing code examples
• To verify documentation accuracy through automated tests
• Before publishing to ensure all examples work correctly

Test Writing Methodology

Follow these four phases to create comprehensive tests for a concept page.

Phase 1: Code Example Extraction

Scan the concept page for all code examples and categorize them:

Category	Characteristics	Action
Testable	Has console.log with output comments, returns values	Write tests
DOM-specific	Uses document, window, DOM APIs, event handlers	Write DOM tests (separate file)
Error examples	Intentionally throws errors, demonstrates failures	Write tests with toThrow
Conceptual	ASCII diagrams, pseudo-code, incomplete snippets	Skip (document why)
Browser-only	Uses browser APIs not available in jsdom	Skip or mock

Phase 2: Determine Test File Structure

tests/
├── fundamentals/              # Concepts 1-6
├── functions-execution/       # Concepts 7-8
├── web-platform/             # Concepts 9-10
├── object-oriented/          # Concepts 11-15
├── functional-programming/   # Concepts 16-19
├── async-javascript/         # Concepts 20-22
├── advanced-topics/          # Concepts 23-31
└── beyond/                   # Extended concepts
    └── {subcategory}/

File naming:

• Standard tests: {concept-name}.test.js
• DOM tests: {concept-name}.dom.test.js

Phase 3: Convert Examples to Tests

For each testable code example:

1. Identify the expected output (from console.log comments or documented behavior)
2. Convert to expect assertions
3. Add source line reference in comments
4. Group related tests in describe blocks matching documentation sections