A modern programming language that makes developers happier.

kotlinlang

We now support JS testing in the current 4.0 snapshot.
Very little configuration required, and the full test life cycle is supported (before/after etc) in addition to options like global asserts, timeouts and test ordering. You can use property testing, table testing, inspectors, nearly all the assertions.
See <https://github.com/kotlintest/kotlintest/tree/master/kotest-examples/kotest-examples-javascript> for a basic example.
(There are some caveats due to limitations in what kotlin-js and the javascript test frameworks allow.)