Mockito has a very nice feature that allows you to verify what parameters were used when a method was executed. For example:

ArgumentCaptor argument = ArgumentCaptor.forClass(Person.class);
verify(mock).doSomething(argument.capture());
assertEquals("John", argument.getValue().getName()); 

However, when using generic typed objects, some problems rise up. For example, the following won't work:

ArgumentCaptor\> argument = ArgumentCaptor.forClass(List.class); 

This is obviously not a Mockito problem, but a generics problem. To solve this, follow these two steps:

  1. use the @Captor annotation.

     @Captor
     private ArgumentCaptor\> argumentCaptor; 
  2. initialize the Mockito annotations in your initialization method (add one if you don't have one)

     @Before
     public void init(){
        MockitoAnnotations.initMocks(this);
     }

And presto! You can now capture the parameters that were used when a to be verified method was executed.

verify(someMock).someMethod(argumentCaptor.capture());
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