Test Gru, part of the broader Gru.ai suite of developer tools, installs as a GitHub app and then works automatically: it detects new or changed code in a pull request, generates relevant unit tests using frameworks like Vitest, Jest, JUnit, pytest, or GoTest depending on the language, runs them, and submits the passing tests as part of the PR. It supports Node.js and TypeScript, Java, Go, and Python.
There's no manual onboarding required beyond installing the GitHub app, which lowers the barrier to trying it compared to tools that need significant configuration before they produce useful output. Gru.ai reports that around 80% of the pull requests Test Gru submits get accepted by maintainers as-is, and that it handles a similar share, roughly 80%, of unit tests in its own team's repository, a meaningful signal that it's dogfooded rather than purely a demo product.
It's free to use, positioning it as a way to boost test coverage incrementally over time rather than requiring a dedicated testing push.