Using Mockito spy in one class to Call static method from another class

Question

Trying to use Mockito's spy function for my JUnit test. I originally had a Class:

public class App1 { 
    public String method1() {
        sayHello();
    }

    public sayHello() {
        Systems.out.println("Hello");
    }
}

Everything in my test class was working correctly with mockito spy on above class:

@Test(expected = IOException.class)
public void testMethod1Failure(){   
    App1 a1 = spy(App1);
    doThrow(IOException.class).when(a1).sayHello();

    a1.method1();
}

But after that i had to switch things around and take sayHello() method into another class to be used as static method:

public class App1 { 
    public String method1() {
        App2.sayHello();
    }
}

public class App2 { 
    public static void sayHello() {
        Systems.out.println("Hello");
    }
}

After this change, my original JUnit testcase is broken and i am unsure how i can use Mockito spy to start App1 that calls the external App2 static method... does anyone know how i can do it? Thanks in advance

Solution

Mockito does not support mocking static code. Here are some ways to handle it:

• Use PowerMockito or similar framework as suggested here: Mocking static methods with Mockito.
• Refactor your code converting static method back to an instance method. As you've found static methods are not easy to Unit test.
• If it's inexpensive to execute actual static method in question then just call it.