Java 模拟 returns null 的私有字段的方法

Question

我正在尝试模拟 return 类型 void 的私有字段的方法。在我的测试中，我试图模拟 aClass.doSomething() 以抛出 IllegalStateException 并且我需要验证是否调用了 recover()。这是一个例子：

public class ClassToTest implements Runnable {
   private ClassToMock aClass;

   @Override
   public void run() {
       try{
           aClass.doSomething("some parameter");
       } catch(IllegalStateException e) {
           logger.error("Something bad happened", e);
           recover();
       }
   }

   public void recover(){
      logger.info("I am recovering");
   }
}

每一个我都分别做了:

模拟私有字段的方法调用
模拟具有 void return 类型的方法
抛出异常
验证私有方法调用

但我无法将所有内容放在一起。感谢任何帮助

Answer 1

我想我应该详细说明 GhostCat 的评论：

Stay with Mockito

Mockito 不仅仅是一个模拟框架 - 它是一门学科。如果您仔细阅读 Mockito 的文档并克制自己不求助于 PowerMock 等，您将学习良好的 OOP 实践。

Read how to do dependency injection with constructors

Primum non nocere - 首先像这样重构您的代码：

public class ClassToTest implements Runnable {

   private final ClassToMock aClass;
   private final Logger logger;

   //injection of collaborators through the constructor
   public ClassToTest(ClassToMock aClass, Logger logger) {
       this.aClass = aClass;
       this.logger = logger;
   }

   @Override
   public void run() {
       try{
           aClass.doSomething("some parameter");
       } catch(IllegalStateException e) {
           logger.error("Something bad happened", e);
           recover();
       }
   }

   public void recover() { //there is no need for this method to be public - see Effective Java item 13
      logger.info("I am recovering");
   }
}

现在您的代码可以使用 Mockito 进行测试而无需求助于更复杂的模拟框架:

//mocks
@Mock ClassToMock classToMock;
@Mock Logger mockLogger;

//system under test
ClassToTest classToTest;

@Before
public void setUp() throws Exception { 
    MockitoAnnotations.initMocks();
    classToTest = new ClassToTest(classToMock, mockLogger);
}

@Test
public void whenRun_thenDoesSomethingWithSomeParameter() {       
    //act
    classToTest.run();

    //assert
    verify(classToMock).doSomething(eq("some parameter"));
}

@Test
public void givenAnIllegalStateForAClass_whenRun_thenLogsError() {       
    //arrange        
    IllegalStateException e = new IllegalStateException();
    when(classToMock.doSomething(anyString()).thenThrow(e); 

    //act
    classToTest.run();

    //assert
    verify(mockLogger).error(eq("Something bad happened"), same(e));
}

@Test
public void givenAnIllegalStateForAClass_whenRun_thenLogsRecovery() {       
    //arrange        
    when(classToMock.doSomething(anyString()).thenThrow(new IllegalStateException()); 

    //act
    classToTest.run();

    //assert
    verify(mockLogger).info(eq("I am recovering"));
}

Java 模拟 returns null 的私有字段的方法

Java mock a method of a private field that returns null

java

junit

mockito

powermock

powermockito