fix: does not pass data provided to mount to wrapper component

[xanf]

#1661 introduced copying of passed options to parent wrapper. However it fails in a weird way if you are using data option for mount/shallowMount with external variable.

i.e.

    const defaultData = { foo: 3 }
    const wrapper = mountingMethod(TestComponent, { data: () => defaultData })

In this case data function will be invoked two times:

• one for Parent component (wrapper for our TestComponent) - at this point defaultData will be "poisoned" (will become reactive, and observed by Parent component for changes)
• one when Parent wrapper will be mounted, causing TestComponent instance to mount - at this point Vue will complain

[Vue warn]: Avoid adding reactive properties to a Vue instance or its root $data at runtime - declare it upfront in the data option.

because defaultData is treated as $data for Parent wrapper component already

In general, we do not need setting data on parent wrapper, so I just eliminate this propety before copying

What kind of change does this PR introduce? (check at least one)

• Bugfix
• Feature
• Code style update
• Refactor
• Build-related changes
• Other, please describe:

Does this PR introduce a breaking change? (check one)

• Yes
• No

If yes, please describe the impact and migration path for existing applications:

The PR fulfills these requirements:

• It's submitted to the dev branch.
• [-] When resolving a specific issue, it's referenced in the PR's title (e.g. fix #xxx[,#xxx], where "xxx" is the issue number)
• All tests are passing: https://github.com/vuejs/vue-test-utils/blob/dev/.github/CONTRIBUTING.md#development-setup
• New/updated tests are included

Other information:

[xanf]

/cc @lmiller1990 as author of #1661

[lmiller1990]

hm, interesting! I guess using an external variable for data is only really something you do in tests?

Either way, seems fine!

[lmiller1990]

It's out

https://github.com/vuejs/vue-test-utils/releases/tag/v1.1.2