PowerMock 单例类

 要测试的方法，调用了一个单例模式写的类。这个类的构造方法又有方法调用，并且j静态成员直接创建。

public class Singleton {

    private static Singleton singleton = new Singleton();

    private Singleton () 
        methodA();
    }

    public void methodA(){    
        // dosomething
    }

    public static Singleton instance(){
        return singleton;
    }
}

public class A {

    public static String methodAA(){
        Singleton.instance().methodA();
        // dosomething
    }

}

@RunWith(PowerMockRunner.class)
@PrepareForTest(Singleton.class)
public ATest {

    @Test
    public void methodAATest() {
        suppressConstructor(Singleton.class);  
        mockStatic(Singleton.class);
        Singleton singleton = mock(Singleton.class);
        when(Singleton.instance).thenReturn(singleton);
        donothing().when(singleton).methoadA();
        A.methoadAA()
    }



}

 参考：Mocking a singleton with EasyMock and PowerMock – Redchilliplus's Blog