What is test-coverage?

A workflow for raising line test coverage in a Flows app to an 80% requirement. Test coverage measures how much of the application code is exercised by automated tests.

Use it when fixing coverage gaps, configuring Vitest or Jest coverage reporting, writing missing tests, or preparing a Flows app for its coverage gate.

It finds uncovered code paths and addresses them by checking the test setup, adding tests, and making code easier to test where needed.

test-coverage — Skill for Claude Code by cognitedata/builder-skills

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

Any agent

npx skills add cognitedata/builder-skills --skill test-coverage

Clone the repo

git clone --depth 1 https://github.com/cognitedata/builder-skills

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/cognitedata/builder-skills/test-coverage/github.svg)](https://agentmods.dev/skills/cognitedata/builder-skills/test-coverage)

Your own site

<a href="https://agentmods.dev/skills/cognitedata/builder-skills/test-coverage"><img src="https://agentmods.dev/badge/skills/cognitedata/builder-skills/test-coverage/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/cognitedata/builder-skills/test-coverage"><img src="https://agentmods.dev/badge/skills/cognitedata/builder-skills/test-coverage.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 103 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 3,771 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe. Third-party audits

Socket pass 18 Sept 2026
Snyk pass 18 Sept 2026
NVIDIA SkillSpector warn 7 Sept 2026

SkillSpector: 8 findings, up to medium

These are SkillSpector’s own severities. On a checked sample its high-severity flags on skills were ~96% false positives — a documented command, a public API, a “never do X” rule — so we show them as a caution to read, not a verdict. Why →

medium MCP Rug Pull · line 105
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 121
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 254
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 287
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 326
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 335
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 105
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]
medium MCP Rug Pull · line 335
npx commands without a version suffix (e.g. @1.0.0) create a rug-pull risk if the upstream server is compromised and publishes a malicious update.

Fix: Pin the version: npx @scope/[email protected]

How audits are shown

Origin original No closer match found in the catalogue.

Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

Model	Per session	Once invoked
Fable 5.1	$0.00103	$0.03771
Opus 5.5	$0.00041	$0.01508
Sonnet 5.5	$0.00021	$0.00754
Haiku 4.5	$0.00010	$0.00377

Measured 2mo ago against content hash 585bb5015156, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

test-coverage scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 2mo ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

skills/test-coverage/SKILL.md · 376 lines

How it starts

The opening of the file, as written. The whole thing — 376 lines — stays where its author put it; the contents beside it link to each section on GitHub.

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:

Install the coverage provider:

pnpm add -D @vitest/coverage-v8

Add the coverage configuration to vitest.config.ts. Read the existing config file, then add the coverage section inside test:

// vitest.config.ts — minimum coverage configuration to add
test: {
  coverage: {
    provider: 'v8',
    reporter: ['text', 'text-summary', 'lcov'],
    include: ['src/**/*.{ts,tsx}'],
    exclude: [
      'src/**/*.test.{ts,tsx}',
      'src/**/*.spec.{ts,tsx}',
      'src/**/vite-env.d.ts',
      'src/main.tsx',
    ],
  },
}

Write the updated config file. If no vitest.config.ts exists at all, create one with the full defineConfig wrapper.

Step 2 — Validate coverage scope

The 80% threshold applies to all .ts and .tsx files under src/, excluding only:

Test files (*.test.ts, *.test.tsx, *.spec.ts, *.spec.tsx)
Type declaration files (vite-env.d.ts)
The entry point (main.tsx)

Apps must not exclude pages, components, hooks, or other production code from coverage measurement.

Read the full file on GitHub · 376 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

2mo ago First seen · 376 lines · 103 tokens per session scan A 585bb5015156

Subscribe to this mod's changes

test-coverage is a skill published in the GitHub repository cognitedata/builder-skills (6 stars, last pushed yesterday), licensed Apache-2.0. It adds 103 tokens to every session and 3,771 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Testing ai-low-risk

test-coverage next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
test-coveragecognitedata/builder-skills	Skill	6	yesterday	Apache-2.0	A	103	Claude Code
imagegenopenai/codex	Skill	134k	today	Apache-2.0	A	113	Codex
playwright-climicrosoft/playwright	Skill	99k	today	Apache-2.0	A	19	Claude Code
local-ai-agentsmicrosoft/ai-agents-for-beginners	Skill	79k	today	MIT	A	200	Claude Code, Codex
systematic-debuggingobra/superpowers	Skill	314k	3d ago	MIT	A	21	Claude Code
next-cache-components-adoptionvercel/next.js	Skill	143k	yesterday	MIT	A	95	Claude Code
next-partial-prefetching-adoptionvercel/next.js	Skill	143k	yesterday	MIT	A	103	Claude Code