Webpack: Use Jest and vue-test-utils

[eddyerburgh]

I'd like to make a PR that replaces mocha and karma with Jest, as well as adding vue-test-utils to the project.

The reasons for Jest over Karma/ mocha:

• Faster
• Less config
• No browser
• No webpack for tests

Another issue is requiring everything the src directory. This installs vue-router, which adds $route as a read only property to the global Vue class. This means people can't stub $route in tests, and if you don't know all the files are required before running the tests, it can be difficult to debug

[LinusBorg]

You have my vote :-P

[eddyerburgh]

I've made a PR to replace karma and mocha. I'll make another PR to add vue-test-utils when it's release

[eddyerburgh]

I've created a vue jest preprocessor that adds source maps. In light of the patent drama, are we still happy to go ahead with replacing Karma and mocha with Jest?

[LinusBorg]

Okay so we got jest included - go get that 1.0.0 release for vue-test-utils and we can close this :)