shallowMount stub behavior is inconsistent between options object component and constructor one

[ktsn]

Version

1.0.0-beta.29

Reproduction link

https://github.com/ktsn/vue-test-utils-shallow-stub-issue

Steps to reproduce

1. yarn install
2. yarn test
3. You will see the inconsistency of stub behavior between options object component and constructor component.

What is expected?

Both shallowMounted component renders the same html.

What is actually happening?

The child of stubbed component (GrandChild) is stubbed if Child is passed as options object while not stubbed if Child is constructor.

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I'm not sure which behavior is intended but I think the behavior with options object stub is more useful. Because sometimes I want to control which child components should be stubs or not by passing the component itself to stubs option. And in that case, I will not expect the child component be rendered entirely (grandchildren components should be replaced with stubs).

[eddyerburgh]

This is actually undefined behavior that I should have considered.

I think the behavior of the constructor is more intuitive, but it might require changing the current shallow rendering logic.

[ebisbe]

#1564 (comment)