fix: vm should be properly typed

[cexbrayat]

This is on top of #64

The types have been tweaked to avoid the need of casting like (wrapper.vm as any).msg.

The test showcases the correct behavior: you can reproduce the issue by adding the test to the master banch. It will:

• not compile without a as any cast
• fail as it returns the vm of the parent which has no msg, isEnabled fields and toggle function.

[cexbrayat]

I splitted the two fixes in 2 separate PRs:

• fix: vm should be the vm of the tested component #64 fixes the vm returned
• this PR improves the typings

[lmiller1990]

Hey, thanks for helping out! Typing this correctly is something I am struggling with. I don't think this is entirely correct, though. wrapper needs to be able to accept objects like :

const Foo = {
  template: '<div>Foo</div>'
}

Not everyone will use defineComponent. With this change, that won't work.

Full error:

const App: {
    render(): VNode<RendererNode, RendererElement>;
}
Argument of type '{ render(): VNode<RendererNode, RendererElement>; }' is not assignable to parameter of type 'new () => ComponentPublicInstance<{}, {}, {}, {}, {}, {}, {}>'.
  Type '{ render(): VNode<RendererNode, RendererElement>; }' provides no match for the signature 'new (): ComponentPublicInstance<{}, {}, {}, {}, {}, {}, {}>'.ts(2345)

🤔

[cexbrayat]

I get your point. Maybe I can simply add an override, so people with defineComponent will have a proper typing and others will be at the same point as now. Most TS users are going to use it anyway, otherwise you don't have proper typings in your components, and we can probably improve later.

[cexbrayat]

@lmiller1990 PTAL: I added a simple override instead of changing the signature. So everything works the same, but, if you use defineComponent, you get proper typings of vm

[lmiller1990]

one comment/question, thanks!

[lmiller1990]

thanks @cexbrayat I will give this a quick test tmr and get it merged.

While we are here, can we get typings in the props mounting options? I was able to do that in an experiment I built prior to this, found here

Eg then we could do

mount(Foo, {
  props: { 
    bar: 'sadf' // <= can we get typesafety here? that would be cool as
  }
})

If this is difficult to accomplish don't worry about it too much for now, but I agree, we should provide as many typings as possible.

[lmiller1990]

eg: component: new () => ComponentPublicInstance<P> (or something)

[cexbrayat]

Sure, I'll try to look into it soon, and I'll open a dedicated PR 👌

[cexbrayat]

@lmiller1990 FYI I added some typings tests using tsd in #72 , improved the typing of vm some more in #73 and started working on properly typings the props options in #74

[lmiller1990]

Awesome, love it. TS changed my life.

I will do the next alpha when the oustanding PRs are merged in and the new Vue alpha comes out since we are waiting on a few bugfixes there.