Mockito - Injecting a List of mocks

Annotate it with @Spy instead of @Mock. As Mockito cannot spy on an interface, use a concrete implementation, for example ArrayList. During test setup add the mocks to the List spy. This way you do not need to alter your test subject solely for test purposes.

@InjectMocks
private Wrapper testedObject = new Wrapper();

@Spy
private ArrayList<Strategy> mockedStrategies;

@Mock
private StrategyA strategyA;

@Mock
private StrategyB strategyB;

@Before
public void setup() throws Exception {
    mockedStrategies.add(strategyA);
    mockedStrategies.add(strategyB);
}

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);
}

You should not mock collections.

Create the mocks you need and put them into a list:

private List<Strategy> strategies; // not mocked!

@Mock
StrategyA strategyA;

@Mock
StrategyB strategyB;

@Before
public void setup(){
  strategies= Arrays.asList(strategyA,strategyB);
  testedObject.strategies= strategies;
}

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