如何在不创建新对象的情况下测试私有成员对象

Question

我正在尝试针对一个类编写单元测试。我无法更改课程，但我认为可以使用反射进行测试。我只是不知道该怎么做。这是课程：

public class MyClass extends AnotherClass implements TheInterface
{
    private enum SomeTypes
    {
        SAMPLE01, SAMPLE02, SAMPLE03
    }

    private CircularList<SomeTypes> someTypesList; 
    Date date= new Date();
    private SomeOtherClassProcessor01 someOtherClassProcessor01;
    private SomeOtherClassProcessor02 someOtherClassProcessor02;
    private SomeOtherClassProcessor03 someOtherClassProcessor03;

    public Properties initialize (Properties properties) throws Exception
    {
        Properties propertiesToReturn = super.initialize(properties);
        someTypesList = new CircularList<SomeTypes>    (Arrays.asList(SomeTypes.values())); 
        someOtherClassProcessor01 = new SomeOtherClassProcessor01(); 
        someOtherClassProcessor02 = new SomeOtherClassProcessor02(); 
        someOtherClassProcessor03 = new SomeOtherClassProcessor03(); 

        return propertiesToReturn;
    }

    @Override
    public void get(ImportedClass someParams) throws Exception
    {
        SomeTypes types = someTypesList.getFirstAndRotate();

        switch(types)
        {
            case SAMPLE01:
            someOtherClassProcessor01.doSomething(someParams,     date);
            break;
            case SAMPLE02:
            someOtherClassProcessor02.doSomething(someParams,     date);
            break;
            case SAMPLE03:
            someOtherClassProcessor03.doSomething(someParams,     date);
            break;
            default:
            throw new IllegalArgumentException("This " + types + "     was not implemented.");
        }
    }   
}

对于我的测试，这是我目前所做的......不确定如何实际做到这一点。

@RunWith(PowerMockRunner.class)
@PrepareForTest(MyClass.class)
public class TestingMyClass
{
    MyClass mockMyClass;
    SomeOtherClassProcessor01 someOtherClassProcessor01;
    SomeOtherClassProcessor02 someOtherClassProcessor02;
    SomeOtherClassProcessor03 someOtherClassProcessor03;
    Date date;


    @Before
    public void initialize () throws Exception
    {
        mockMyClass = spy(new MyClass()); 
        mockSomeOtherClassProcessor01 =     mock(SomeOtherClassProcessor01.class);
        mockSomeOtherClassProcessor02 =     mock(SomeOtherClassProcessor02.class);
        mockSomeOtherClassProcessor03 =     mock(SomeOtherClassProcessor03.class);
    }

    @Test
    public void testingGet() throws Exception
    {
        date = new Date(); 
        //this is where I'm stuck
        Whitebox.setInternalState(mockMyClass,     "someOtherClassProcessor01", mockSomeOtherClassProcessor01);

    }
}

是否可以为此使用白盒？我需要确保在这些对象的 getter 中有一个调用。我应该尝试类似 when(someOtherClassProcessor01.doSomething(any(), date)).thenReturn(true) 吗？如果您需要更多详细信息，请告诉我。

编辑：甚至可以模拟私有枚举 SomeTypes？

Answer 1

一种选择是使用反射将您自己的（模拟的）SomeOtherClassProcessor 实现替换为 MyClass：

MyClass myClass = new MyClass();
SomeOtherProcessor01 mockProcessor01 = mock(SomeOtherProcessor01.class);

// reflection bit: find the field by its name
// handle NoSuchFieldException
Field someProcessorField = MyClass.getDeclaredField("someOtherProcessor01");
// the field is declared as private, so make it accessible in order to work with it
someProcessorField.setAccessible(true);
// now set your mocked processor into the field. 
// First argument is the object to change; second argument - new value for the field
someProcessorField.set(myClass, mockProcessor01);

PS。使用 PowerMock 和/或反射是屈服于糟糕的设计（根据 Timothy :)。您不应该依赖尚未经过良好测试的代码，如果是，您不应该再次尝试测试它。假设您的测试实际上揭示了一个错误 - 如果您不控制代码，您将如何修复它？假设 Java 11 变成了一个东西并且禁止你使用反射。假设您正在测试的代码发生更改并且字段被重命名 - 使用反射，您没有编译时安全性......潜在问题的列表还在继续