Test Coverage Improver

Points you at uncovered code and gives you test templates to fill the gaps. Runs coverage reports through Jest, Vitest, or NYC, then provides ready-to-use patterns for unit tests, async functions, mocks, and React components. The branch coverage checklist is actually helpful since that's usually what tanks your numbers. Includes sensible threshold configs (80% lines, 75% branches) and prioritizes what to test first: critical paths like auth and payments, then complex logic, then edge cases. More useful as a reference when you're staring at a coverage report wondering what to write next than as an automated solution.

skills.sh installs: 306
GitHub stars: 422
last updated: Aug 21, 2026

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Install

$ npx -y skills add onewave-ai/claude-skills --skill test-coverage-improver --agent claude-code

Installs into .claude/skills of the current project.

Files

Test Coverage Improver

Instructions

When improving test coverage:

Run coverage report to identify gaps
Prioritize critical/complex code paths
Write tests for uncovered code
Verify coverage improved

Generate Coverage Report

# Jest
npx jest --coverage

# Vitest
npx vitest --coverage

# NYC (Istanbul) for any test runner
npx nyc npm test

# View HTML report
open coverage/lcov-report/index.html

Coverage Targets

Type	Minimum	Good	Excellent
Lines	70%	80%	90%+
Branches	60%	75%	85%+
Functions	70%	80%	90%+
Statements	70%	80%	90%+

Test Templates

Unit Test (Jest/Vitest)

import { describe, it, expect, vi, beforeEach } from 'vitest';
import { calculateTotal, formatCurrency } from './utils';

describe('calculateTotal', () => {
  it('should sum all item prices', () => {
    const items = [
      { price: 10, quantity: 2 },
      { price: 5, quantity: 1 },
    ];
    expect(calculateTotal(items)).toBe(25);
  });

  it('should return 0 for empty array', () => {
    expect(calculateTotal([])).toBe(0);
  });

SKILL.md on GitHub