我如何模拟提供被 JMockit 模拟的类的实例的静态方法? [英] how do i mock the a static method that provides an instance of the class being mocked with JMockit?

问题描述

我正在尝试模拟一个单例类 (SessionDataManager)，在该类中我通过调用静态 getInstance() 方法获取实例，但所有尝试似乎都返回 null.

I'm trying to mock a singleton class (SessionDataManager) where I get an instance by calling the static getInstance() method but all attempts seem to return null.

我试过了

    @Mocked SessionDataManager sessionDataManager;

或

        new MockUp<SessionDataManager>(){
            @Mock
            public SessionDataManager getInstance(Invocation invocation) {

                return invocation.getInvokedInstance(); 
            }
        };

我得到相同的结果 = null;

I get the same result = null;

有人可以提出解决方案吗?

Can anyone suggestion a solution?

谢谢

推荐答案

我建议查看文档，但这里有两个完整的示例测试:

I would suggest having a look at the documentation, but here are two complete example tests:

public final class ExampleTest {
    public static final class SessionDataManager {
        private static final SessionDataManager instance = new SessionDataManager();
        public static SessionDataManager getInstance() { return instance; }
        public void doSomething() { throw new UnsupportedOperationException("to do"); }
    }

    @Test
    public void mockingASingleton(@Mocked SessionDataManager mockInstance) {
        SessionDataManager singletonInstance = SessionDataManager.getInstance();

        assertSame(mockInstance, singletonInstance);
        singletonInstance.doSomething(); // mocked, won't throw
    }

    @Test
    public void mockingASingletonWithAMockUp() {
        new MockUp<SessionDataManager>() {
            // no point in having a @Mock getInstance() here
            @Mock void doSomething() { /* whatever */ }
        };

        SessionDataManager singletonInstance = SessionDataManager.getInstance();
        singletonInstance.doSomething(); // redirects to the @Mock method, won't throw
    }
}

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