Perform LayoutClick on a HorizontalLayout

I added a LayoutClickListener to a HorizontalLayout. This works fine.
Now I want to create a JUnit test to ensure that things happens correctly with clicking on this HorizontalLayout.
So the question is: How can I perform a LayoutClick??

For example for a Button it's easy:
Button testButton = new Button("Test");
testButton.click();

Answert still needed..