Test Coverage

This one automates the grind of hitting 80% line coverage for Flows apps. It doesn't just run a report and leave you hanging. It configures Vitest or Jest coverage tooling if it's missing, audits your exclude rules to catch overly broad exemptions (like hiding entire component or page directories), then writes the actual missing test files for hooks, services, and utilities. It knows to use renderHook with QueryClientProvider wrappers for React hooks and vi.mock for services. If tests are broken, it fixes imports and mocks before measuring coverage. Useful when you're staring at a 60% coverage gate failure and need to close the gap without spending half a day figuring out which files have no tests.

skills.sh installs: 1.9K
GitHub stars: 6
last updated: Aug 21, 2026

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Install

$ npx -y skills add cognitedata/builder-skills --skill test-coverage --agent claude-code

Installs into .claude/skills of the current project.

Files

Test Coverage Fix

Fix test coverage for $ARGUMENTS (or the whole app if no argument is given). This skill enforces the 80% line coverage hard gate required for Flows app approval by finding AND fixing coverage gaps. Work through every step in order.

Step 1 — Verify test framework and coverage tooling

Check that the project has a working test framework with coverage configured:

# Check for vitest or jest in package.json
grep -E "(vitest|jest)" package.json

# Check for coverage configuration
cat vitest.config.ts 2>/dev/null || cat vitest.config.js 2>/dev/null || cat jest.config.ts 2>/dev/null || cat jest.config.js 2>/dev/null

Verify:

A test framework (Vitest or Jest) is installed and configured
The config file has a coverage section (e.g. coverage: { provider: 'v8', ... } in vitest.config.ts)
A coverage reporter is configured (at least text and lcov or json-summary)

If coverage tooling is not configured, fix it now: