feat: create stubs in createElement

[eddyerburgh]

• Stub components during $createElement call. This way we will always stub components, including dynamically added components

• Extend components during $createElement call. This avoids the previous recursive lookup, and ensures we only extend components that are rendered

• Use tag in stub name

• Fixes Warning messages thrown about child components created with vue.extend even when parent component is mounted with shallowmount #973

• Fixes Unknown custom element: <router-link> when using mount() #994

• Fixes Using a <component> tag does not stub the component when using shallowMount #995

Breaking change: this will change the output of some stubs

[afv]

Hello!

After this change I'm getting stubbed components on mounted (not shallow) components if the component was previously shallow mounted (on another test).

it('renders the component without stubs', () => {
  const wrapper = mount(TheComponent, { store, localVue, propsData: {…} });
  // The component has no stubs, as expected
}

it('renders the component again without stubs', () => {
  const wrapper = mount(TheComponent, { store, localVue, propsData: {…} });
  // The component has no stubs, as expected
}

But:

it('renders the component with stubs', () => {
  const wrapper = shallowMount(TheComponent, { store, localVue, propsData: {…} });
  // The component has stubs, as expected
}

it('renders the component with stubs, unexpected', () => {
  const wrapper = mount(TheComponent, { store, localVue, propsData: {…} });
  // The component has stubs too!
}

Why? 😕

[eddyerburgh]

The bug has been reported—#1050

Follow that thread for updates