Testing

We use vitest for testing library code.

Configuring this properly was tricky. Since the library heavily relies on browser APIs like web workers & wasm, it doesn't really make sense to mock the browser APIs for unit tests. In order for our tests to be trustworthy, we really need them to run in a realistic browser environment.

Vitest browser mode + playwright (provider) seems to satisfy all our needs. It spins up a real browser to run tests and can run headlessly for CI. I had to add one hack to make it work with the web-worker, but otherwise it seems to work well out of the box.

This framework should be suitable for all the additional libraries we have planned (e.g. react).

Usage

# in the root of the repo
pnpm run test

• pnpm test — runs tests in a headless browser
• pnpm test:cov — runs tests and reports coverage
• pnpm test:ui — runs tests in the Vitest UI

When adding new features or fixing bugs, it's important to add test cases to cover the new or updated behavior.