正在测试的同一类中的模拟私有方法

unit-testing mocking java junit jmockit

2022-09-02 22:36:21

我有一个名为的 Java 类，我想用 JUnit 进行测试。我要测试的 public 方法（）在同一类中调用私有方法，以确定要遵循的条件路径。我的目标是为中的不同路径编写 JUnit 测试。另外，调用一个服务，所以我不希望它在运行JUnit测试时实际执行。MyClassmethodAmethodBmethodAmethodB

模拟和控制其返回的最佳方法是什么，以便我可以测试“方法A”的不同路径？methodB

我更喜欢在编写模拟时使用JMockit，所以我对任何适用于JMockit的答案都特别感兴趣。

这是我的示例类：

public class MyClass  {

    public String methodA(CustomObject object1, CustomObject object2)  {

        if(methodB(object1, object2))  {
            // Do something.
            return "Result";
        }

        // Do something different.
        return "Different Result";

    }

    private boolean methodB(CustomObject custObject1, CustomObject custObject2)  {

        /* For the sake of this example, assume the CustomObject.getSomething()
         * method makes a service call and therefore is placed in this separate
         * method so that later an integration test can be written.
         */
        Something thing1 = cobject1.getSomething();
        Something thing2 = cobject2.getSomething();

        if(thing1 == thing2)  {
            return true;
        }
        return false;
    }

}

这是我到目前为止所拥有的：

public class MyClassTest  {
    MyClass myClass = new MyClass();

    @Test
    public void test_MyClass_methodA_enters_if_condition()  {
        CustomObject object1 = new CustomObject("input1");
        CustomObject object2 = new CustomObject("input2");

        //  How do I mock out methodB here to return true?

        assertEquals(myClass.methodA(object1, object2), "Result");
    }

    @Test
    public void test_MyClass_methodA_skips_if_condition()  {
        CustomObject object1 = new CustomObject("input1");
        CustomObject object2 = new CustomObject("input2");

        //  How do I mock out methodB here to return false?

        assertEquals(myClass.methodA(object1, object2), "Different Result");
    }

}

谢谢！

答案 1

不要试图嘲笑私人方法，即使你可以使用嘲笑工具进行欺骗。私有成员是实现详细信息，您可以随意更改。而是使用非私有 API 来练习该类。如果这很麻烦，请考虑将麻烦的代码移动到另一个类中（如果还没有），并使用依赖注入来注入麻烦代码的模拟实现。

答案 2

给出你要求的答案（使用JMockit的部分嘲笑）：

public class MyClassTest
{
    @Tested MyClass myClass;

    @Test
    public void test_MyClass_methodA_enters_if_condition() {
        final CustomObject object1 = new CustomObject("input1");
        final CustomObject object2 = new CustomObject("input2");

        new NonStrictExpectations(myClass) {{
            invoke(myClass, "methodB", object1, object2); result = true;
        }};

        assertEquals("Result", myClass.methodA(object1, object2));
    }

    @Test
    public void test_MyClass_methodA_skips_if_condition() {
        final CustomObject object1 = new CustomObject("input1");
        final CustomObject object2 = new CustomObject("input2");

        new NonStrictExpectations(myClass) {{
            invoke(myClass, "methodB", object1, object2); result = false;
        }};

        assertEquals("Different Result", myClass.methodA(object1, object2));
    }
}

但是，我不建议这样做。一般来说，方法不应该被嘲笑。相反，模拟被测单元的实际外部依赖关系（在本例中为）：privateCustomObject

public class MyTestClass
{
    @Tested MyClass myClass;
    @Mocked CustomObject object1;
    @Mocked CustomObject object2;

    @Test
    public void test_MyClass_methodA_enters_if_condition() {
        new NonStrictExpectations() {{
            Something thing = new Something();
            object1.getSomething(); result = thing;
            object2.getSomething(); result = thing;
        }};

        assertEquals("Result", myClass.methodA(object1, object2));
    }

    @Test
    public void test_MyClass_methodA_skips_if_condition() {
        new NonStrictExpectations() {{
            object1.getSomething(); result = new Something();
            object2.getSomething(); result = new Something();
        }};

        assertEquals("Different Result", myClass.methodA(object1, object2));
    }
}