Installation

Your coding agent can install Supercov for you. If you’d like to set it up yourself, choose your language above and follow these steps in your project.

For setup, runner support and a runnable example in one place, use the JavaScript / TypeScript, Python, Ruby or Rust guide.

Before you start

Node.js 22 or newer is required for the npm package. Your project’s test dependencies and any services used by the suite must already be available.

The native CLI supports macOS, Linux and Windows on arm64 and x64. See Runner support for environment-specific limits.

Get Supercov

The npm package runs on demand with npx; a global installation isn't needed. This command downloads Supercov if necessary and prints its version:

npx supercov --version

npx uses the npm registry. The package provides a prebuilt native CLI; it doesn't compile Supercov on install.

No account or Supercov configuration file is required.

Run your tests

From the project root, put Supercov before your normal test command:

npx supercov -- npm test

Everything after -- is your existing test command. Use the command you normally run for the full suite, including its usual flags. Supercov measures that run; it doesn’t add tests by itself.

Read the result:

npx supercov runs latest

You’ll see line, branch and MC/DC coverage where measurement is supported. Assertion coverage also needs your agent to build an assertion map.

Continue with your agent

Use the prompt in Getting started to add one missing test, or ask the agent to inspect the run you’ve just made. Reports stay local in .supercov/; see Files and privacy for details.

If installation or the test command fails, start with Troubleshooting.