private void closeStage() {
    Stage stage = ((Stage) workbench.getScene().getWindow());
    stage.fireEvent(
        new WindowEvent(
            stage,
            WindowEvent.WINDOW_CLOSE_REQUEST
        )
    );
  }
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