Testing vue-cli javascript components with jest and yarn: nearest does not work

To run jest in vue-cli apps, one cannot use jest directly (see explanation):

Note that directly running jest will fail because the Babel preset requires hints to make your code work in Node.js, so you must run your tests with vue-cli-service test:unit.

To make this a little bit more complicated, I use yarn for my dependency management. This means to run tests I have to do:

yarn test:unit [jest options]

I configured vim-test to do this:

let test#javascript#jest#executable = 'yarn test:unit'

But the problem is that the jest script passes -- explicitly as a command line arg. For example the resulting command run is:

yarn test:unit --no-coverage -t '^ApplicationForm\.vue test descriptions$' -- tests/unit/components/ApplicationForm.spec.js

This unfortunately tests the whole file tests/unit/components/ApplicationForm.spec.js, not only the example I wanted to run. The reason is:

yarn outputs this warning:

Warning From Yarn 1.0 onwards, scripts don't require "--" for options to be forwarded. In a future version, any explicit "--" will be forwarded as-is to the scripts.

It seems to ignore everything before the two dashes --, so in fact it runs:

yarn test:unit tests/unit/components/ApplicationForm.spec.js

When I remove the two dashes -- manually, it works like expected (and yarn does not output a warning):

yarn test:unit --no-coverage -t '^ApplicationForm\.vue test descriptions$' tests/unit/components/ApplicationForm.spec.js

The general questions are:

• Do you want to detect a vue-cli app and yarn automatically in this case and do everything right automatically without configuration? A starting point could be to search for @vue/cli-plugin-unit-jest in package.json to detect the use of jest in combination with vue-cli and a yarn.lock for yarn
• If not, is adding a config option to the jest test runner to not add those two dashes -- an option? (this would simply solve my problem at least)
• How can this scenario be handled in a neat way?

Start by reading the JavaScript Jest runner and its command construction, then compare the configured yarn test:unit command with the package.json and yarn.lock detection described in the issue. Check how the explicit -- is added and determine the intended configuration or automatic handling; done means Jest options and the test path are forwarded correctly for this Vue CLI and Yarn scenario.