@Test
public void should_be_OK_when_calling_real_method_on_concrete_class() throws Throwable {
//given
ArrayList mock = mock(ArrayList.class);
mock.clear();
Invocation invocationOnClass = new MockitoCore().getLastInvocation();
//when
validator.validate(new CallsRealMethods(), invocationOnClass);
//then no exception is thrown
}