Imported un-transpiled module is not transpiled when component under test is mounted

[MartinPeverelli]

Version

3.0.0-beta.15

Reproduction link

https://github.com/MartinPeverelli/reproduction-component

Steps to reproduce

• git clone git@github.com:MartinPeverelli/reproduction-component.git
• npm install
• npm run test:unit

What is expected?

Tests should pass

What is actually happening?

Tests fail with the following:

(function (exports, require, module, __filename, __dirname) { import ReproductionModule from './ReproductionModule'
                                                              ^^^^^^
SyntaxError: Unexpected token import

---

Custom module ReproductionModule is not transpiled.
The serve and build processes work as expected, but the test:unit process does not transpile the imported component on the fly.

Added as issue here, as requested: vuejs/vue-test-utils#689 (comment)