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test-coverage-specialist

Measure JavaScript and TypeScript test coverage with Vitest or Jest and generate reports.

Updated Aug 23, 2026
Search Tags:#vitest#test coverage#branch coverage#ci#coverage report#c8#istanbul
One-click install
npx skills add https://github.com/Whaleylaw/llm-lawyer --skill test-coverage-specialist
Or copy as Structured Prompt for Agent▼
Please help me install this Agent Skill.
Skill: test-coverage-specialist
Source: https://github.com/Whaleylaw/llm-lawyer/tree/main/.claude/skills/test-coverage-specialist
Command: npx skills add https://github.com/Whaleylaw/llm-lawyer --skill test-coverage-specialist

SYSTEM DOCUMENTATION & REQUIREMENTS

What problem does it solve?

This Skill helps engineering teams measure and improve test coverage, identify untested code paths and branches, and enforce coverage thresholds so regressions are caught before merging.

Core Features & Use Cases

  • Configure coverage providers and thresholds for Vitest or Jest, choosing c8 or Istanbul as the provider.
  • Generate human-readable HTML reports, machine-readable lcov/json outputs, and CI-ready summaries to find red (uncovered) and yellow (partially covered) lines.
  • Integrate with CI to fail builds below per-file or global thresholds and upload coverage artifacts to Codecov or Coveralls for trend tracking.
  • Prioritize tests for critical business logic, error paths, and branch coverage to raise overall reliability.

Quick Start

Run the test suite with coverage enabled, open the HTML report, and add tests for uncovered branches and critical files.

Frequently Asked Questions about test-coverage-specialist

High-intent search queries and answers about installing and using this skill.

FAQPage Schema
How do I enforce per-file test coverage thresholds in CI for Vitest?▼

Vitest measures test coverage using c8 or Istanbul providers to identify untested files and uncovered branches, then generates HTML, lcov, JSON, and text reports to visualize red and yellow uncovered lines.

How do I generate lcov and HTML coverage reports for JavaScript projects?▼

Upload generated lcov coverage artifacts from your CI pipeline directly to Codecov or Coveralls to monitor coverage trends and track regressions across merges.

Does this test coverage approach work with both Jest and Vitest?▼

Prioritize tests for critical business logic and error paths by analyzing branch coverage reports to identify partially covered yellow lines and raise overall codebase reliability.

What is the difference between c8 and Istanbul for measuring branch coverage?▼

The difference between c8 and Istanbul lies in their coverage collection mechanisms, but both can be configured as providers in Vitest or Jest to measure branch coverage and enforce thresholds.

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