Files and privacy

Supercov runs locally. It doesn’t require an account or upload your source, tests or coverage reports to a Supercov service. Your coding agent’s own data handling is separate; check its settings and provider policy.

What changes in your project

Supercov stores reports, execution data and assertion assessments under .supercov/, which it excludes from Git. Your agent’s test edits are ordinary repository changes that you can review, commit or discard.

Supercov measures an instrumented copy of the project. It does not overwrite your source files with instrumented code.

The test command still has its normal side effects. A test can write a file, update a snapshot, call a service or modify a database. Supercov is not a sandbox for arbitrary commands; use the same precautions as an ordinary test run.

For JavaScript, TypeScript and Rust, new or modified command outputs in the isolated workspace are copied back, with exceptions for instrumented source and deletions. A change a formatter or fixer in your test command makes to a source file (prettier --write, eslint --fix) reaches your project when the command ends. Python and Ruby run in place, so test-command file changes and deletions happen directly in your project.

Run suites at the same time

You can run several Supercov commands in one project at once, such as unit and end-to-end suites in parallel CI steps. Each run works in its own copy of the project, so none waits for another. Combine them afterwards with merge:

npx supercov -- <unit test command> &
npx supercov -- <end-to-end test command> &
wait
npx supercov merge

With no run named, merge combines the runs recorded on the current code. Extra copies are removed a day after their last run, or with npx supercov runs clean.

To add new tests without running the whole suite again, measure only the new tests and run merge. Helpers and test runner settings changed with them keep an earlier run when its tests don’t load them, or when the change only adds functions or a timeout. The CLI guide lists what counts.

What uses the network

The first npx supercov invocation may contact the npm registry to download the package.

Your tests and coding agent may also use the network. Supercov’s local storage doesn’t change how those tools connect to external services.

Keep or remove reports

Run reports let the agent compare results and revisit earlier work. They may include file paths, source excerpts and assertion details, so treat them as project data when sharing an archive or filing an issue.

Long-running tasks can accumulate reports and build caches. Ask the agent to show what cleanup would remove before approving it, and keep any runs you still need for a comparison. See Speed and storage for cleanup options and Runs and evidence for the stored files.