Squire.js | friendly dependency injector for testing Require | REST library

I have some ES5 example project that I would like to convert to ES6:

https://github.com/stefaneidelloth/testDemoES5

https://github.com/stefaneidelloth/testDemoES6

The examples include a class Qux which inherits from a class Baa.

When testing Qux, I would like to mock Baa.

For ES5 I use Squire.js to mock AMD module dependencies and the unit tests work just fine.

Unfortunately I could not find a testing framework that supports ES6 (="ECMAScript 2015 Language", ES2015) modules directly. We now have 2020 and there are still no unit tests for ES2015? I already spend a lot of time trying to get these tests working ... and I have the impression that my approach is missing something.

Since I could not find direct support for ES6 tests, I try to stick to karma and use webpack to translate the ES6 module code to ES5 AMD modules for testing.

Lets first consider to use karma in combination with requirejs and ES6 code that has been translated to AMD modules.

A. If I try to mock a translated class Baa (module 'src/baa') with Squire ... that does not work any more. Webpack puts all dependencies in a single file and when using 'src/qux', my injected 'src/baa' is not considered.