### Question:
StackableStage extends Stage { public void pop(int n) { stack.pop(n); } StackableStage(Viewport viewport, ScreenStack stack);  StackableStage(Viewport viewport); ScreenStack getScreenStack(); void replace(Actor screen); void push(Actor screen); void pop(int n);  }### Answer:
@Test public void pop() { stage.pop(2); verify(stack).pop(eq(2)); }