If you removed all code changes in the PR, this test will still pass, because there is nothing asserting that the listener is called.

And this test is not a unit test anymore (if the EventDispatcher gets broken, it will make this test fail).
You should mock the dispatcher instead, and assert that an event is dispatched with the right data in it. It will fix both issues (and also catch the fact that a different implementation of the interface cannot be used currently if you mock the interface properly instead of the implementation)