Mockito - Injecting a List of mocks

fascynacja :

I have the following code:

@Component 
public class Wrapper
{ 
    @Resource 
    private List<Strategy> strategies;

    public String getName(String id)
    {
    // the revelant part of this statement is that I would like to iterate over "strategies"
        return strategies.stream()
            .filter(strategy -> strategy.isApplicable(id))
            .findFirst().get().getAmount(id);
    } 
}

@Component 
public class StrategyA implements Strategy{...}

@Component 
public class StrategyB implements Strategy{...}

I would like to create a Test for it using Mockito. I wrote the test as follows:

@InjectMocks
private Wrapper testedObject = new Wrapper ();

// I was hoping that this list will contain both strategies: strategyA and strategyB
@Mock
private List<Strategy> strategies;

@Mock
StrategyA strategyA;

@Mock
StrategyB strategyB;

@Test
public void shouldReturnNameForGivenId()
{   // irrevelant code...
    //when
    testedObject.getName(ID);
}

I am getting NullPointerException on line:

filter(strategy -> strategy.isApplicable(id))

, which states that the "strategies" list is initialized but is empty. Is there any way Mohito will behave in the same wasy as Spring? Adding automatically all instances implementing interface "Strategy" to the list?

Btw I do not have any setters in Wrapper class and I would like to leave it in that way if possible.

thopaw :

Mockito can not know that you want to put somthing in the List strategies.

You should rethink this an do something like this

@InjectMocks
private Wrapper testedObject = new Wrapper ();

private List<Strategy> mockedStrategies;

@Mock
StrategyA strategyA;

@Mock
StrategyB strategyB;

@Before
public void setup() throws Exception {
    mockedStrategies = Arrays.asList(strategyA, strategyB);
    wrapper.setStrategies(mockedStrategies);
}