Most functions are easy to test and still go untested, because writing the first test file is the slow part: the imports, the fixtures, the mock setup. This writes that file. Paste a function, pick a language, a framework and a mocking style, and get a suite back — the happy path plus the boundaries the code itself suggests, like empty inputs, missing fields and the error branches. The output goes into an editor so you can read it, copy it, or download it as a test file.

JavaScript, TypeScript, Python and others, with framework choices including Jest, Vitest, Mocha and pytest

They are written to run against the code you pasted, but import paths depend on your project layout — expect to adjust those. Read generated tests before trusting them, as you would any generated code

Yes — choose no mocking, the framework's own mocks, or hand-written stubs