@Test
  void initNavigationDrawer() {
    // verify no NPE is thrown by the listener when setting a null control
    workbench.setNavigationDrawer(null);
  }
Internal utility method for testing.
Simulates closing the stage, which fires a close request to test logic
inside of {@link Stage#setOnCloseRequest(EventHandler)}.
Using {@link FxRobot#closeCurrentWindow()} would be better, but it only works on Windows
because of its implementation, so this approach was chosen as a workaround.
@see <a href="https://github.com/TestFX/TestFX/issues/447">
closeCurrentWindow() doesn't work headless</a>
workbenchfx-core/src/test/java/com/dlsc/workbenchfx/WorkbenchTest.java