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);
}