What is the current behavior?

MockDoc bubbles DOM events to parentElement every time during simulation, completely ignoring the special boundary rules of the Shadow DOM. For example, with the following DOM structure:

parent-host (Shadow Host)
  └── #shadow-root (Shadow Root) 
      └── child-host

When the event bubbles from the child-host, its parentElement is null, but its container is the shadow-root, and shadow-root.host points to the parent-host.

GitHub Issue Number: #5676

What is the new behavior?

According to the W3C specification, when the event is set to composed: true, it can cross Shadow DOM boundaries.

Therefore, for the DOM structure example above, the correct bubbling path should be: child → shadow-root → shadow-host → parent.

Documentation

Does this introduce a breaking change?

• Yes
• No

Testing

Test Coverage:

Added consistency test: New test src/mock-doc/test/shadow-dom-event-bubbling.spec.ts.

Test Results:

✅ All 3 tests in the modified test file pass

Manual Verification:

In this minimal reproducible example, after linking @stencil/core and re-running npm run test, the previously failing test case my-parent: logs 3 separate steps to the console has now succeeded.

Other information