Clarify docs on how to mock $root

[aantipov]

What problem does this feature solve?

The docs say that I can use mocks mounting option to mock "global injections" like $route.

I considered $root as a "global injection" and that I can use mocks to mock it. Unfortunately it didn't work for me, I spent lots of time trying to make it working, without any success. In the end I came up with a solution to use parentComponent option to mock $root.

As far as I understood it's not possible to mock $root using mocks and it's not considered as a bug.

If I'm right, then the docs for mocks need clarification stating that clearly and providing a way to mock $root

What does the proposed API look like?

The docs should say smth like this:

"One can't use mocks to mock $root though. If you need to mock $root, use "parentComponent" option instead."

And provide "parentComponent" section with an example how to mock $root

[lmiller1990]

I don't think $root is really a global injection in the same way Vuex and VueRouter are; global injection here really should be written as "properties injected by third party plugins, assigned to Vue.prototype".

I think a PR adding a note about $root would be a great idea.. I don't think we need a whole section dedicated to mocking $root; this isn't a very common use case, afaik, and the docs are already pretty bloated with a lot of information.

[aantipov]

@lmiller1990
We, developers, all come with a different background and see at things from a different perspective.
So your point may be true for some and not for others.

Irrespective of that, I see the "Mounting Options" documentation covering all possible cases when you need to provide/mock some of the component data (arguments, data, methods, slots, components, etc.).
The only missing part is $root, and from the documentation it's not clear why can't one use mocks and should use parentComponent instead, it's not trivial at all.

I might agree that the need in mocking $root might not come often, but still it happens and it would be good for the docs to cover that use case.

I try prepare the PR, if I have time

[lmiller1990]

@aantipov I agree, everyone has different backgrounds - I can see why you might expect mocks to work with $root. Happy for a PR adding a note about this (I think under the mocks section in the API docs would be best). You could include a link to the issue with the work around.

Will mark this as "good first issue" so someone else can pick it up if you don't have time. Thanks!