How to verify that specific class method was passed as parameter?

Question

In class MyClass that I test I have:

public void execute(){
    service.call(ThisClass::method1);
}

And following:

void method1(){do 1;}
void method2(){do 2;}

And in test:

@Mock
Service service;

@Test
public void testCallMethod1()
{
     MyClass myClass = new MyClass();
     myClass.execute();

     service.verify(any(Runnable.class));
}

And it works, but, how do I verify that parameter instead of any Runnable was method1 and not method2?

I'm looking for solution that will look like (For example, not really works):

service.verify(eq(MyClass::method1.getRunnable()))

Answer 1

The following works for me:

public class MyTest {

public static class X{
    static void method1() {};
    static void method2() {};
}

@Test
public void throwAway() {
  ExecutorService service = mock(ExecutorService.class);
  Runnable command1 = X::method1;
  Runnable command2 = X::method2;
  service.execute(command1);
  verify(service).execute(command1);
  verify(service, never()).execute(command2);
}

}

The key was extracting the method reference lambda and using it in both the execution and the verify. Otherwise, each "::" operator produces a distinct lambda instance which doesn't work with equality testing, as some of the comments above discussed the semantics of lambda equality.