code-coverage

A test-coverage tool that measures which code paths have tests and creates tests for important uncovered areas. Test coverage shows how much of a program's code is exercised by tests.

In plain words
What is it for?
Use it with JavaScript, Python, Go, or Rust projects to run available coverage tools, inspect results, find missing tests, and generate tests for critical gaps.
Why use it?
It reveals untested functions, branches, and error paths that may hide bugs before release.

Skill for Claude CodeCodex

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.

agentmods
npx agentmods add skills/viknesh20-20/claude-code-tool-kit/code-coverage
Any agent
npx skills add viknesh20-20/claude-code-tool-kit --skill code-coverage
Clone the repo
git clone --depth 1 https://github.com/viknesh20-20/claude-code-tool-kit

Made for: Claude Code, Codex.

Per session 33 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 720 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
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.

ModelPer sessionOnce invoked
Fable 5 $0.00033 $0.00720
Opus 5 $0.00016 $0.00360
Sonnet 5 $0.00007 $0.00144
Haiku 4.5 $0.00003 $0.00072

Measured 2d ago against content hash e63ebe737c34, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

code-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 2d 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.

.claude/skills/code-coverage/SKILL.md · 79 lines

How it starts

The opening of the file, as written. The whole thing — 79 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Test Coverage Analysis

Detect Test Setup

!ls package.json jest.config.* vitest.config.* .nycrc* .c8rc* .coveragerc* setup.cfg pyproject.toml tox.ini 2>/dev/null !cat package.json 2>/dev/null | grep -E "jest|vitest|c8|nyc|istanbul|coverage" | head -5


Process

Step 1: Run Coverage (if configured)

Attempt to run the project's coverage command:

Ecosystem Coverage Command
npm (Jest) npx jest --coverage --json 2>/dev/null
npm (Vitest) npx vitest run --coverage 2>/dev/null
npm (c8) npx c8 report --reporter=json 2>/dev/null
Python (pytest) python -m pytest --cov --cov-report=json 2>/dev/null
Go go test -coverprofile=coverage.out ./... 2>/dev/null && go tool cover -func=coverage.out
Rust cargo tarpaulin --out json 2>/dev/null

If coverage tools aren't configured, proceed with static analysis.

Step 2: Static Analysis (if no coverage tool)

For the target file(s):

  1. Identify all public functions, methods, and classes
  2. Search for corresponding test files
  3. For each function, check if there's a test that calls it
  4. Map which code paths (branches, error handlers) have test coverage

Step 3: Coverage Report

Summary
Metric Value
Line coverage XX%
Branch coverage XX%
Function coverage XX%
Uncovered files X
Uncovered Critical Code

List the most important uncovered code, prioritized by:

  1. Business logic — core features and workflows
  2. Error handling — catch blocks, error paths, edge cases
  3. Security-sensitive — auth, input validation, data access
  4. Complex logic — functions with high cyclomatic complexity

For each uncovered area:

  • File path and line numbers
  • What the code does
  • Why it's important to test
  • Suggested test cases

Step 4: Generate Missing Tests

For the top 5 most critical uncovered areas, generate test code following the project's test patterns (same structure as /write-tests).

Read the full file on GitHub · 79 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.

  1. 2d ago First seen · 79 lines · 33 tokens per session scan A e63ebe737c34

Subscribe to this mod's changes

code-coverage is a skill published in the GitHub repository viknesh20-20/claude-code-tool-kit (7 stars, last pushed 4mo ago), licensed MIT. It adds 33 tokens to every session and 720 once invoked, about $0.0002 per session on Opus 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.

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