Free Unit Test Generator

Paste a function signature below and click Generate Test to get a ready-to-run test scaffold — Jest for JavaScript, pytest for Python — with clear TODOs for the real inputs and expected outputs.

About this Unit Test Generator

Starting a test file from a completely blank page is one of the most common reasons tests get skipped. This Unit Test Generator removes that friction: paste a function signature and it instantly produces a correctly structured test file — imports, a describe/it block for Jest, or properly named test functions for pytest — with the plumbing already in place so you can focus on the part that actually matters: real inputs and expected outputs.

This is intentionally a scaffold, not a claim of automatically-generated coverage. The tool cannot know what your function is supposed to return for a given input, so every scaffold includes clear TODO markers where you fill in the specifics.

Why start from a scaffold instead of writing tests from scratch

• Removes the "blank file" friction that causes tests to be skipped or postponed
• Guarantees correct file structure and naming conventions for the framework
• Reminds you to cover edge cases, not just the happy path

Jest vs pytest basics

Jest is the default test framework for most JavaScript and TypeScript projects: tests are grouped in describe() blocks and individual cases use it() or test(), with assertions via expect(value).toBe(...). pytest is the equivalent for Python: test files and functions are prefixed with test_, and assertions use the plain assert keyword rather than a matcher API.

How to fill in the TODOs

• Pick a realistic "typical" input for your function and manually compute (or run it) the expected output.
• Add edge cases: empty input, null/None, zero, negative numbers, very large inputs.
• If the function throws on invalid input, add a test that asserts it throws/raises.

Tips for good test coverage

Aim for at least one happy-path test and one edge-case test per function, and prefer many small, focused tests over one large test that checks everything at once — it makes failures much easier to diagnose.

FAQ: Unit Test Generator