jest-testing-skill

Set up Jest 30+ with TypeScript for unit tests, integration tests, mocking (jest.fn, jest.mock, jest.spyOn), coverage configuration, custom matchers, snapshot testing, and setup/teardown patterns.

Quality

81%

Does it follow best practices?

Impact

—

No eval scenarios have been run

Securityby

Passed

No known issues

Quality

Content

79%

Reviews the quality of instructions and guidance provided to agents. Good implementation is clear, handles edge cases, and produces reliable results.

This is a strong, actionable Jest testing skill with excellent executable examples covering the full testing spectrum from unit tests to integration tests with MSW. The main weaknesses are the lack of explicit validation/troubleshooting workflows and the monolithic structure that could benefit from splitting advanced topics into separate files.

Suggestions

Add a 'Verify Setup' section with explicit validation steps (e.g., 'Run npx jest --version to confirm installation', 'Create a minimal test to verify config works')

Add a 'Troubleshooting' section covering common failures like ESM/CJS conflicts, transform errors, and mock not working scenarios

Consider splitting MSW integration and database testing into separate reference files (e.g., MOCKING_HTTP.md, DATABASE_TESTING.md) with links from the main skill

Dimension	Reasoning	Score
Conciseness	The skill is lean and efficient, providing executable code examples without explaining basic concepts Claude already knows. Every section earns its place with practical, copy-paste ready configurations and patterns.	3 / 3
Actionability	Fully executable code throughout - complete Jest configs, test examples with proper imports, mocking patterns, and CLI commands. All examples are copy-paste ready with real TypeScript syntax.	3 / 3
Workflow Clarity	While individual patterns are clear, the skill lacks explicit validation checkpoints. There's no guidance on verifying test setup works correctly, no troubleshooting steps for common failures, and no feedback loops for debugging failing tests.	2 / 3
Progressive Disclosure	Content is well-organized with clear sections, but it's a monolithic document (~300 lines). The MSW mocking section and integration patterns could be split into separate reference files. References to other skills (vitest-testing-skill, github-actions-ci) are mentioned but inline content is heavy.	2 / 3
	Total	10 / 12 Passed

Description

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 description with excellent specificity and trigger term coverage for Jest testing with TypeScript. The main weakness is the absence of an explicit 'Use when...' clause, which would help Claude know exactly when to select this skill over others. The technical depth and version specificity make it highly distinctive.

Suggestions

Add a 'Use when...' clause such as 'Use when setting up Jest tests, configuring test coverage, writing mocks, or when the user mentions Jest, testing with TypeScript, or test configuration.'

Dimension	Reasoning	Score
Specificity	Lists multiple specific concrete actions: 'unit tests, integration tests, mocking (jest.fn, jest.mock, jest.spyOn), coverage configuration, custom matchers, snapshot testing, and setup/teardown patterns' - these are all concrete, actionable capabilities.	3 / 3
Completeness	Clearly answers 'what does this do' with comprehensive capabilities, but lacks an explicit 'Use when...' clause or equivalent trigger guidance explaining when Claude should select this skill.	2 / 3
Trigger Term Quality	Includes excellent natural keywords users would say: 'Jest', 'TypeScript', 'unit tests', 'integration tests', 'mocking', 'jest.fn', 'jest.mock', 'jest.spyOn', 'coverage', 'snapshot testing' - covers both high-level concepts and specific API terms.	3 / 3
Distinctiveness Conflict Risk	Very specific niche: Jest 30+ with TypeScript. The version specificity (30+) and technology combination (Jest + TypeScript) plus detailed feature list make it clearly distinguishable from generic testing skills or other test framework skills.	3 / 3
	Total	11 / 12 Passed

Validation

90%

Warnings & errors only

Checks the skill against the spec for correct structure and formatting. All validation checks must pass before discovery and implementation can be scored.

Validation — 10 / 11 Passed

Validation for skill structure

Criteria	Description	Result
frontmatter_unknown_keys	Unknown frontmatter key(s) found; consider removing or moving to metadata	Warning

	Total	10 / 11 Passed

Repository: achreftlili/deep-dev-skills
Commit: 181fcbc

Reviewed: 4 months ago

Table of Contents

Discovery Implementation Validation

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