Support firing events inside of custom element shadow DOM

[hontas]

• @testing-library/user-event version: 11.2.1
• Testing Framework and version:
  • @open-wc/testing version 2.5.17
  • lit-html version 1.2.1
  • mocha version 6.2.3
• DOM Environment: Chrome@83.0.4103.97

Relevant code or config

const el = render('custom-element');
const input = el.shadowRoot.querySelector('input');
userEvent.type(input, 'hello');

What you did:
I used userEvent.type with on an input-element inside a custom element's shadow DOM (in order to test its internal event listeners).

What happened:
Events did not fire on the input.

Reproduction repository:

Problem description:
The currentElement-helper returns element.ownerDocument.activeElement which return the custom element host instead of the focused element inside its shadow DOM. I'm guessing this is intended ;) but it is causing problems in this case, and it's not how the real DOM behaves when writing in an input-element inside a custom element.

Suggested solution:
Modify the currentElement-helper to return activeElement inside shadow DOM.

PR on its way :)

[kentcdodds]

🎉 This issue has been resolved in version 11.3.0 🎉

The release is available on:

• npm package (@latest dist-tag)
• GitHub release

Your semantic-release bot 📦🚀