Added test combining watch and shouldUpdate

[tjallingt]

Small thought i had while working on this: // eslint-disable-next-line no-unused-expressions these are necesairy in watch because its kind of strange, should watch not just be an array of properties to watch and be implemented as watch.map(prop => this[prop])?

[coveralls]

Coverage remained the same at 100.0% when pulling f2fa3d5 on tjallingt:master into 99ff44c on foxbenjaminfox:master.

[coveralls]

Coverage remained the same at 100.0% when pulling f2fa3d5 on tjallingt:master into 99ff44c on foxbenjaminfox:master.

[foxbenjaminfox]

I've merged this PR, and I've published these changes as v3.4.0 to npm.

You're right about the fact that the way watch is implemented is not the best. It's the kind of thing that sounds great at the time, but in retrospect could be a lot cleaner. The way it currently works takes advantage of Vue's reactivity system in (what seems like) a neat way, but it's not really worth the hassle, because it doesn't really add much beyond doing it the simple way (with an array of properties.)

An array of properties can't do this:

const vm1 = new Vue({ data: { x: 0 } })
const vm2 = new Vue({
  data: { x: 1 },
  asyncComputed: {
    y: {
      get () { return this.x },
      watch () { vm1.x }
    }
  }
})

Ultimately though, that's an extreme edge case, and you probably shouldn't be doing that anyway. So I do consider the current way watch works to be a mistake, and if I did it again I would do it the simpler and better way, as an array of properties instead of a function.

Well, redoing watch is certainly something I'll think about for v4, when I decide that it's worth releasing a major version bump, with backwards-compatibility breaking changes. That will happen eventually, and when it comes I may well do an update to the watch interface as part of that.

[foxbenjaminfox]

Thanks for the PRs. I appreciate it.

If you ever feel like making some more, feel free to do so anytime. I'm always happy to receive good contributions to my projects.