Ruby on Rails 5.1 & Vue.js 2.4.x – Testing with Karma, Jasmine – How to install? [bounty on stackoverflow]

I asked the same Question on stackoverflow

I have Rails 5.1.x and Vue.js 2.4.x; I do not mix Rails and Vue.js in the frontend – only Vue.js is used

I added the following packages:

package.json

...
"devDependencies": {
    "jasmine": "^2.8.0",
    "karma": "^1.7.1",
    "karma-chrome-launcher": "^2.2.0",
    "karma-jasmine": "^1.1.0",
    "webpack-dev-server": "^2.6.1"
  },
...

Q1: Where do I do the configuration? In webpack/test.js or some karma.conf.js file

Q2: What is in this conf file?

Q3: Do I need to install karma-webpack?

I updated my Question on stackoverflow and added a bounty