包含抽象val成员的模拟Scala特性 [英] Mocking Scala traits containing abstract val members

问题描述

我正在按照Martin Fowler的演示模型模式编写一个Swing应用程序.

I am writing a Swing application following Martin Fowler's Presentation Model pattern.

我创建的特征包含由Swing组件已经实现的方法的抽象声明:

I create traits that contain abstract declarations of methods already implemented by Swing components:

trait LabelMethods {
  def setText(text: String)
  //...
}

trait MainView {
  val someLabel: LabelMethods
  def setVisible(visible: Boolean)
  // ...
}

class MainFrame extends JFrame with MainView {
  val someLabel = new JLabel with LabelMethods
  // ...
}

class MainPresenter(mainView: MainView) {
  //...
  mainView.someLabel.setText("Hello")
  mainView.setVisible(true)
}

如何使用一种开源的模拟框架( EasyMock ， Mockito ， JMockit 等)进行单元测试?是否有另一个模拟框架，也许特定于Scala可以做到这一点?

How can I mock the someLabel member of the MainView trait using one of open-source mocking frameworks (EasyMock, Mockito, JMockit, etc.) for unit testing? Is there another mocking framework, perhaps specific to Scala that can do this?

推荐答案

H！在通勤的家中找到了它:-).

Hah! Figured it out on the commute home :-).

Scala允许具体类中的val覆盖特征中的def.

Scala allows a val in a concrete class to override a def in a trait.

我的特质变成:

trait LabelMethods {
  def setText(text: String)
  //...
}

trait MainView {
  def someLabel: LabelMethods    // Note that this member becomes
                                 // a def in this trait...
  def setVisible(visible: Boolean)
  // ...
}

我的MainFrame类不需要更改:

class MainFrame extends JFrame with MainView {
  val someLabel = new JLabel with LabelMethods // ...But does not change
                                               // in the class
  // ...
}

我的测试用例代码如下:

My test case code looks like this:

class TestMainPresenter {
  @Test def testPresenter {
    val mockLabel = EasyMock.createMock(classOf[LabelMethods])

    val mockView = EasyMock.createMock(classOf[MainView])
    EasyMock.expect(mockView.someLabel).andReturn(mockLabel)
    //... rest of expectations for mockLabel and mockView

    val presenter = new MainPresenter(mockView)
    //...
  }
}

请注意，我尚未对此进行实际测试，但它应该可以工作:-).

Note that I have not actually tested this, but it should work :-).

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