java - 如何创建支持重绘功能的JFrame/JPanel模拟

我对Swing应用程序的单元测试有一些问题。
我想做的是将可绘制对象传递给我的JPanel，每次执行此操作时，它都应该重新绘制自身。

对于基本场景而言，已经非常多了，现在进入我的单元测试：

public class GraphicViewImplTest {

    private JFrame frame;
    private GraphicViewImpl view; //This is my JPanel
    private GraphicLineSpy firstGraphicLine;
    private Line firstLine;

    @Before
    public void setUp() throws Exception {
        frame = new JFrame();
        view = new GraphicViewImpl();
        frame.add(view);
        frame.setVisible(true);
        firstLine = new Line();
        firstLine.setStart(new Point(11, 12));
        firstLine.setEnd(new Point(21, 22));
        firstGraphicLine = new GraphicLineSpy(firstLine);
    }

    @Test
    public void whenReceivingLine_shouldPaintLine() {
        view.receiveShape(firstGraphicLine);
        assertTrue(firstGraphicLine.wasPainted());
    }

}

如您所见，我正在将GraphicLineSpy传递给视图。 GraphicLine类基本上是Line类的装饰器，该类知道如何在Swing中绘制线。 GraphicLineSpy覆盖了GraphicLine的paint方法，只是将标志设置为true，因此我可以检查是否调用了paint方法。

现在开始我的GraphicView JPanel的实现：

public class GraphicViewImpl extends JPanel implements GraphicView, Observer {

    protected GraphicViewPresenter presenter;
    protected List<GraphicShape> graphicShapeList = new LinkedList<>();

    @Override
    public void receiveShape(GraphicShape graphicShape) {
        graphicShapeList.add(graphicShape);
        graphicShape.addObserver(this);
        repaint();
    }

    @Override
    public void removeShape(GraphicShape graphicShape) {
        graphicShapeList.remove(graphicShape);
        graphicShape.removeObserver(this);
        repaint();
    }

    public void setPresenter(GraphicViewPresenter presenter) {
        this.presenter = presenter;
    }

    @Override
    public void update() {
        repaint();
    }

    @Override
    public void paintComponent(Graphics graphics) {
        super.paintComponent(graphics);
        for (GraphicShape graphicShape : graphicShapeList)
            graphicShape.paint(graphics);
    }
}

现在，我的问题是，当我运行这些测试时，他们说我的GraphicLine没有涂漆。但是，当我实际运行该程序并添加新的GraphicLine时，它工作得很好，我的所有Shape都被绘制了。我在测试设置中缺少什么吗？

而且，这可能是最重要的部分，我想这并不是每次运行测试时启动整个JFrame的最佳解决方案，所以我想知道如何最好地创建一个不会破坏的测试双整个重画功能。

预先感谢您的任何提示！

最佳答案

我认为您应该专注于测试代码而不是JPanel实现，因此您应该使用Mockito框架（或任何其他框架）来模拟其他依赖项：

public class GraphicViewImplTest {

    @Rule
    public MockitoRule rule = MockitoJUnit.rule();
    @Mock
    private Graphics2D graphics; // not tested dependency
    @Mock
    private GraphicShape firstLine; // not tested dependency

    private GraphicViewImpl view; //This is my JPanel

    @Before
    public void setUp() throws Exception {
        view = spy(new GraphicViewImpl());
        doNothing().when(view).repaint();
    }

    @Test
    public void whenReceivingLine_shouldPaintLine() {
        view.receiveShape(firstGraphicLine);
        verify(view).repaint();
        verify(firstLine,never()).paint(graphics);

        view.paintComponent(graphics);
        verify(firstLine).paint(graphics);
    }
}