Microsoft has open sourced code-testing-generator, a polyglot agent that writes unit tests and then proves they work. It ships in the dotnet-test plugin inside the MIT-licensed dotnet/skills repository.
The agent targets a gap that coding assistants usually leave open. A prompt like ‘generate unit tests’ does not say which framework, file location or assertions to use. code-testing-generator settles those decisions by reading the repository before it writes anything. It then plans, writes, runs and checks the tests it produces. On Microsoft’s internal 152-task benchmark, it completed 140 tasks against 120 for stock GitHub Copilot. Both setups used the same model and prompts.
Is it deployable
Yes. It is an agent definition along with skills, not a hosted service, so it runs inside your existing coding agent and code stays local.
Company stage: viable from solo maintainers upward. Startups and mid-market teams gain most, because the agent supplies repository research a small team has no time to encode. Enterprises can fork the language guidance to match internal frameworks.
