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Agent skill

Supercov

by sickn33 in sickn33/agentic-awesome-skills

Measure line, branch and MC/DC coverage of a project's existing tests with the supercov CLI, then write small, focused tests for the code no test reaches.

MITAuto-check passedTesting & QA

Install Supercov

skills CLI
$ npx skills add sickn33/agentic-awesome-skills --skill supercov -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install sickn33/agentic-awesome-skills supercov --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/sickn33/agentic-awesome-skills.git skills-src && mkdir -p .claude/skills && cp -r skills-src/skills/supercov .claude/skills/supercov && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
supercov
GitHub stars
47k
Used in
1 other repo
Token cost
~1.3k tokens
SKILL.md length
671 words
Files
1
Skills in repo
1,354
Repo updated
First seen
Licence
MIT

At a glance

Measure line, branch and MC/DC coverage of a project's existing tests with the supercov CLI, then write small, focused tests for the code no test reaches.

  • Works in 4 steps: Measure the suite → Pick a target → Write one focused test → …
  • Testing & QA work in your project
  • SKILL.md covers Overview, When to Use This Skill, Preconditions and How It Works, plus 6 more sections
  • Calls npx, npm and cargo; needs TYPESAFE_API_KEY

What it does

Supercov is an agent skill from sickn33/agentic-awesome-skills. Measure line, branch and MC/DC coverage of a project's existing tests with the supercov CLI, then write small, focused tests for the code no test reaches.

Its SKILL.md is about 1.3k tokens, which your agent loads only when the skill is triggered. It is a single SKILL.md file with no bundled scripts.

It sits in Testing & QA. The repository describes itself as: AAS Core is the local, agent-first control plane for complete catalog discovery, agent-owned selection, stack validation, and planning, backed by 2,400+ agentic skills. Includes… The licence is MIT.

When your agent uses it

  • Testing & QA work in your project

Example prompts

  • “/supercov”

Requirements

  • Node.js
  • A credential in TYPESAFE_API_KEY

Workflow steps

4 steps, taken from the step headings in SKILL.md.

  1. Measure the suite
  2. Pick a target
  3. Write one focused test
  4. Rerun and report

What it can do on your machine

Read from SKILL.md and the folder at commit ec02547. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    Shell commands in SKILL.md call:

    • npx
    • npm
    • cargo

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md. Its commands use npx and npm, which can reach the network depending on how they are called.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names these keys or tokens, usually read from environment variables:

    • TYPESAFE_API_KEY

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Supercov loads about 1.3k tokens when it runs. Until then it costs about 41 tokens; SKILL.md has 671 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~41
When it runs · the whole SKILL.md, loaded when a task matches
~1.3k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

The full file from sickn33/agentic-awesome-skills at commit ec02547, republished under its MIT licence (© sickn33). 671 words, ~1,315 tokens.

Download SKILL.mdSave it as .claude/skills/supercov/SKILL.md (or your agent's skills folder).
name
supercov
description
Measure line, branch and MC/DC coverage of a project's existing tests with the supercov CLI, then write small, focused tests for the code no test reaches.
category
testing
risk
critical
source
https://github.com/supercorp-ai/supercov/tree/main/plugins/supercov/skills/supercov
source_repo
supercorp-ai/supercov
source_type
community
date_added
2026-10-04
author
Supercorp
tags
testing, coverage, mcdc, test-generation
tools
claude, cursor, gemini, codex
license
MIT

Supercov

Overview

Supercov runs the project's own test command on the user's machine and reports line, branch and MC/DC coverage per test. It changes no source, tests or configuration. This skill uses that report to pick one untested piece of code at a time and write a focused test for it.

It works with JavaScript, TypeScript, Python, Ruby, Rust, Go, Java and Kotlin projects.

When to Use This Skill

  • Use when the user asks to add or improve tests.
  • Use when the user asks which code is untested, or asks to raise coverage.
  • Use when the user asks which file to refactor first and has agreed to a quality check (see "Quality check").

Preconditions

  • Node.js 22 or newer. If it is missing, tell the user. Do not install software without the user's approval.
  • The project's test command, for example npm test, pytest or cargo test. Ask if it is not obvious from the repository.
  • Always run the pinned version, npx supercov@3.0.4. The first run downloads that release from npm, so get the user's approval before it.

How It Works

Step 1: Measure the suite

Run the full test command under Supercov. Coverage is measured locally and sends nothing over the network.

bash
npx supercov@3.0.4 -- npm test
Step 2: Pick a target

List the untested code, pick one item, and read it in context.

bash
npx supercov@3.0.4 runs latest gaps --limit 5
npx supercov@3.0.4 runs latest file src/session.js
Step 3: Write one focused test

Write one test for the chosen target. Change only test files unless the user asks otherwise.

Step 4: Rerun and report

Rerun the command from step 1. Report the test you added and the coverage before and after.

For anything not shown here, npx supercov@3.0.4 docs <topic> prints the guide for that version. Topics: agent-loop, quality, supported-suites, troubleshooting.

Examples

Example 1: Add a test for untested code
bash
npx supercov@3.0.4 -- npm test
npx supercov@3.0.4 runs latest gaps --limit 5
# add one test for the first gap, then:
npx supercov@3.0.4 -- npm test
Example 2: Other languages
bash
npx supercov@3.0.4 -- pytest
npx supercov@3.0.4 -- cargo test
npx supercov@3.0.4 -- go test ./...
npx supercov@3.0.4 -- ./gradlew test

Quality check

npx supercov@3.0.4 quality ranks files by code smells, and npx supercov@3.0.4 quality patch reports what a change introduced.

  • These two commands send the project's source files to TypeSafe's API for analysis. Run them only when the user asked for a quality check, and tell the user before running that their source files will be sent to TypeSafe.
  • They need the user's own TYPESAFE_API_KEY in the environment. Never ask the user to paste a key into the conversation, and never create, read or print one.
  • If the key is missing, tell the user the check needs it, then answer from reading the code and say Supercov did not check it.
Show full SKILL.md (265 more words)Show less

Best Practices

  • ✅ Measure the full suite first, so the gaps reflect every test.
  • ✅ Add one test per gap and rerun before picking the next.
  • ✅ Report coverage before and after with the numbers Supercov printed.
  • ❌ Don't change application code to raise coverage unless the user asks.
  • ❌ Don't run the quality commands without the user's request and consent.

Limitations

  • Coverage shows which code ran under a test. It does not show that the test checked the result.
  • Supercov measures the suites listed in npx supercov@3.0.4 docs supported-suites. Other runners are not measured.
  • The test command runs as the project defines it. If the suite needs services, credentials or network access, those needs still apply.
  • This skill does not replace environment-specific validation, testing, or expert review.
  • Stop and ask for clarification if required inputs, permissions, or safety boundaries are missing.

Security & Safety Notes

  • The skill runs the project's own test command and writes test files in the user's repository. Run it only in a repository the user has authorized, and keep changes to test files unless the user asks otherwise.
  • Supercov writes its run data to a .supercov directory in the project. It does not edit source, tests or configuration.
  • npx supercov@3.0.4 downloads a pinned release from the npm registry. Get the user's approval before the first run. Upgrading the pin needs a new review.
  • Coverage commands make no network requests. Only the quality commands contact a third party, TypeSafe's API, and only with the user's consent and their own key.
  • @test-driven-development - Use when the behavior does not exist yet and the test should come first.

© sickn33, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

Just SKILL.md in skills/supercov of sickn33/agentic-awesome-skills.

Open the folder on GitHubat commit ec02547

Used in 1 other repository

We found 5 copies of this SKILL.md (exact, near-identical or edited) in other folders, from 1 other GitHub owner. This page covers the copy in sickn33/agentic-awesome-skills, which our catalogue first saw on October 7, 2026.

Compare with similar skills

Supercov next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Supercov compared with similar skills
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Supercov this skillsickn33/agentic-awesome-skills47k1 repos~1.3kAutomated safety check: PassMIT
Web Application Testinganthropics/skills180k51 repos~966Automated safety check: PassApache-2.0
Diagnosing Bugsfossasia/eventyay-interpretation1.6k32 repos~2.1kAutomated safety check: PassApache-2.0
TDDpietheinstrengholt/rssmonster56430 repos~906Automated safety check: PassMIT
TDD WorkflowhellangleZ/burn-in-cceverywhere-ralph11211 repos~2.4kAutomated safety check: PassNone
TDDsanity-io/sanity6.4k20 repos~1kAutomated safety check: PassMIT

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Categories

Questions about Supercov

What does Supercov do?

Measure line, branch and MC/DC coverage of a project's existing tests with the supercov CLI, then write small, focused tests for the code no test reaches. Supercov is an agent skill from sickn33/agentic-awesome-skills. Measure line, branch and MC/DC coverage of a project's existing tests with the supercov CLI, then write small, focused tests for the code no test reaches.

When should I use Supercov?

Supercov fits situations like: testing & QA work in your project.

How do I install Supercov in Claude Code?

Run `npx skills add sickn33/agentic-awesome-skills --skill supercov -a claude-code`. Or copy the skill folder (skills/supercov in sickn33/agentic-awesome-skills) into .claude/skills/supercov in your project. Claude Code loads it when a task matches its description.

How do I install Supercov in Codex?

Run `npx skills add sickn33/agentic-awesome-skills --skill supercov -a codex`. Or copy the skill folder (skills/supercov in sickn33/agentic-awesome-skills) into .agents/skills/supercov in your project. Codex loads it when a task matches its description.

Can I use Supercov in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add sickn33/agentic-awesome-skills --skill supercov -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/supercov, .gemini/skills/supercov, .github/skills/supercov and .opencode/skills/supercov in your project.

What does Supercov need to run?

Going by SKILL.md and its folder, Supercov needs the command-line tools its instructions call (npx, npm and cargo) and credentials named TYPESAFE_API_KEY. Our summary lists: Node.js; A credential in TYPESAFE_API_KEY.

Does Supercov access the network?

SKILL.md contains no URLs. Its commands use npx and npm, which can reach the network depending on how they are called. This is read from the text; nothing was executed.

Is Supercov safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Supercov use?

Supercov is published under the MIT licence (declared in SKILL.md). It allows redistribution, so the full SKILL.md is shown on this page.

How many tokens does Supercov use?

About 1.3k tokens (SKILL.md is roughly 5.3k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full.

What are the alternatives to Supercov?

Skills that share tags, products or a category with Supercov: Web Application Testing (anthropics/skills, 180k stars), Diagnosing Bugs (fossasia/eventyay-interpretation, 1.6k stars), TDD (pietheinstrengholt/rssmonster, 564 stars) and TDD Workflow (hellangleZ/burn-in-cceverywhere-ralph, 112 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Supercov?

sickn33 (a GitHub user) maintains it in sickn33/agentic-awesome-skills, which has 47,343 GitHub stars. The repository holds 1,354 skills in this directory. The repository was last updated on October 7, 2026.

Source: sickn33/agentic-awesome-skills on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.