### What problem does this feature solve? I would like to see in my snapshot that I call my childcomponent with correct prop. ``` <childcomponent-stub child-Prop="'some propsData that needs to be tested'"/> ```` Here is a failing test with my expected snapshot: https://codesandbox.io/s/ql77047m9q ### What does the proposed API look like? nothing to add here <!-- generated by vue-issues. DO NOT REMOVE -->