引发异常的PowerMockito调用私有方法失败

Question

I try to mock following method foo in class MyClass :

private Class<?> foo(final String str) throws ClassNotFoundException{
    return Class.forName(str);
}

So I wrote:

MyClass pl = PowerMockito.spy(new MyClass());

try {
    PowerMockito.when(pl, PowerMockito.method(MyClass.class, "foo", String.class))
                .withArguments(anyString())
                .thenReturn(Boolean.TRUE.getClass());
} catch (Exception e) {
    e.printStackTrace(); // catch ClassNotFoundException
}

It doesn't work and throws Exception java.lang.reflect.InvocationTargetException .

However, if i'll replace return Class.forName(str) with return Boolean.TRUE.getClass(); in foo method - everything is ok.

How to tell to PowerMockito to invoke method foo that throws Exception on failure?

Answer 1

1. if you dont need real method call , and you can work with mock - change spy() to mock()

MyClass pl = PowerMockito. spy(new MyClass()) ;

MyClass pl = PowerMockito. mock(MyClass.claa) ;

and your code works without any changes , except spy/mock.

2. if you need SPY() with real method call

do this:

MyClass pl = PowerMockito.spy(new MyClass());

    try {
        PowerMockito.doReturn(Boolean.TRUE.getClass())
                .when(pl, PowerMockito.method(MyClass.class, "foo", String.class))
                .withArguments(anyString());
    } catch (Exception e) {
        e.printStackTrace(); // catch ClassNotFoundException
    }

---

However, if i'll replace return Class.forName(str) with return Boolean.TRUE.getClass(); in foo method - everything is ok.

this works due to 1. it's call a real metho , 2. you retrun Boolean class . but when you call with anyString() it calls real method and pass null as value.

read Important gotcha on spying real objects! :):)