Description

We've been using mocha for our JS testing library. While Mocha is a very compact, battle-tested library, it can be challenging for those unfamiliar with the JS ecosystem, as it does not provide features such as assertion or mocking. Therefore, it is required to combine Mocha with other libraries such as chai, and sinon.

As Pyodide contributors are often those who are more familiar with Python than JS, I think it would be nice if we could use a more popular, full-featured testing library such as Jest or vitest. I think those libraries provide more beginner-friendly, all-in-one APIs.

Goal

Replace mocha with jest or vitest, also remove chai and sinon from the dev dependencies.