### Question:
LevelChoiceServiceImpl implements LevelChoiceService { @Override public void moveRight() { if (currentScreen < screenCount - 1) { currentScreen++; } updateAll(); } LevelChoiceServiceImpl(int levelCount, int levelPerScreen); @Override void moveRight(); @Override void moveLeft(); @Override void moveTo(int screen); @Override void attach(Observer observer); @Override int getCurrentScreen(); @Override boolean isLastScene(); @Override boolean isFirstScene();  }### Answer:
@Test public void moveRight() { sut.moveRight(); sut.moveRight(); assertThat(sut.getCurrentScreen(), is(2)); sut.moveRight(); assertThat(sut.getCurrentScreen(), is(2)); verify(observer, times(3)).update(); }