@Override
  public Pixel[] getPixels() {
    return pixels;
  }
@Test
  void testGetPixels() {
    try {
      var field = FrameBuffer.class.getDeclaredField("pixels");
      var pixels = new Pixel[FrameBuffer.HEIGHT * FrameBuffer.WIDTH];
      Arrays.fill(pixels, Pixel.WHITE);
      pixels[0] = Pixel.BLACK;
      var frameBuffer = new FrameBuffer();
      field.setAccessible(true);
      field.set(frameBuffer, pixels);
      assertEquals(pixels, frameBuffer.getPixels());
    } catch (NoSuchFieldException | IllegalAccessException e) {
      fail("Fail to modify field access.");
    }
  }