vitest-testing-skill
Set up Vitest 2.x with TypeScript for unit and component testing using test/describe/it, vi.fn/vi.mock/vi.spyOn, component testing with Testing Library, coverage (v8/istanbul), workspace config, and snapshot testing.
Install with Tessl CLI
npx tessl i github:achreftlili/deep-dev-skills --skill vitest-testing-skill76
Does it follow best practices?
If you maintain this skill, you can automatically optimize it using the tessl CLI to improve its score:
npx tessl skill review --optimize ./path/to/skillValidation for skill structure
Discovery
82%Based on the skill's description, can an agent find and select it at the right time? Clear, specific descriptions lead to better discovery.
This is a strong, technically specific description that clearly identifies the tool (Vitest 2.x), language (TypeScript), and comprehensive feature set. The main weakness is the absence of an explicit 'Use when...' clause that would help Claude know when to select this skill over other testing-related skills.
Suggestions
Add a 'Use when...' clause with trigger phrases like 'Use when setting up Vitest, configuring test coverage, writing unit tests with vi.mock, or adding Testing Library for component tests'
Consider adding file extension triggers like '.test.ts', 'vitest.config.ts' to help with file-based skill selection
| Dimension | Reasoning | Score |
|---|---|---|
Specificity | Lists multiple specific concrete actions: 'Set up Vitest 2.x with TypeScript', 'unit and component testing', 'test/describe/it', 'vi.fn/vi.mock/vi.spyOn', 'component testing with Testing Library', 'coverage (v8/istanbul)', 'workspace config', and 'snapshot testing'. | 3 / 3 |
Completeness | Clearly answers 'what does this do' with comprehensive feature list, but lacks an explicit 'Use when...' clause or equivalent trigger guidance explaining when Claude should select this skill. | 2 / 3 |
Trigger Term Quality | Includes strong natural keywords users would say: 'Vitest', 'TypeScript', 'unit testing', 'component testing', 'Testing Library', 'coverage', 'vi.mock', 'vi.fn', 'snapshot testing'. These are terms developers naturally use when setting up testing. | 3 / 3 |
Distinctiveness Conflict Risk | Very specific to Vitest 2.x with TypeScript - the combination of specific tool (Vitest), version (2.x), language (TypeScript), and detailed features (vi.fn, vi.mock, Testing Library) creates a clear niche unlikely to conflict with other testing skills. | 3 / 3 |
Total | 11 / 12 Passed |
Implementation
64%Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.
This is a highly actionable Vitest skill with excellent, executable code examples covering unit tests, component tests, mocking, and advanced patterns like MSW. However, it's overly long for a SKILL.md overview, mixing essential patterns with advanced topics that should be in separate files. The lack of a clear setup workflow with validation steps and the monolithic structure reduce its effectiveness as a quick reference.
Suggestions
Split advanced topics (MSW integration, workspace config, test database setup) into separate referenced files like ADVANCED.md or MSW.md, keeping SKILL.md as a concise overview
Add a numbered 'Getting Started' workflow with explicit validation steps (e.g., '1. Install deps, 2. Create config, 3. Run `npx vitest` to verify setup works, 4. Add first test')
Remove explanatory comments in code examples that state the obvious (e.g., '# For React component testing') and trim redundant pattern variations
| Dimension | Reasoning | Score |
|---|---|---|
Conciseness | The skill is comprehensive but includes some unnecessary verbosity, such as explaining what Testing Library is for and basic concepts Claude would know. The content could be tightened by removing explanatory comments and consolidating similar patterns. | 2 / 3 |
Actionability | Excellent actionability with fully executable, copy-paste ready code examples throughout. Every pattern includes complete, working TypeScript code with proper imports, and the scaffold commands are immediately usable. | 3 / 3 |
Workflow Clarity | While individual patterns are clear, there's no explicit workflow for setting up a new project from scratch with validation checkpoints. The 'Common Commands' section lists commands but doesn't sequence them into a coherent setup/development workflow. | 2 / 3 |
Progressive Disclosure | The content is well-organized with clear sections, but it's a monolithic document (~400 lines) that could benefit from splitting advanced topics (MSW setup, workspace config, database setup) into separate referenced files. No external file references are provided. | 2 / 3 |
Total | 9 / 12 Passed |
Validation
81%Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.
Validation — 9 / 11 Passed
Validation for skill structure
| Criteria | Description | Result |
|---|---|---|
skill_md_line_count | SKILL.md is long (534 lines); consider splitting into references/ and linking | Warning |
frontmatter_unknown_keys | Unknown frontmatter key(s) found; consider removing or moving to metadata | Warning |
Total | 9 / 11 Passed | |
- Reviewed
Table of Contents
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