@Mock和@InjectMocks之间的区别

Question

@Mock和@InjectMocksMockito框架有什么区别？

Answer 1

@Mock创建一个模拟。@InjectMocks创建该类的实例，并将使用@Mock（或@Spy）注释创建的模拟注入该实例。

请注意，您必须使用@RunWith(MockitoJUnitRunner.class)或Mockito.initMocks(this)初始化这些模拟并注入它们。

@RunWith(MockitoJUnitRunner.class)

public class SomeManagerTest {

    @InjectMocks

    private SomeManager someManager;

    @Mock

    private SomeDependency someDependency; // this will be injected into someManager

     //tests...

}

Answer 2

这是一个关于如何一个示例代码@Mock和@InjectMocks作品。

假设我们有Game和Player类。

class Game {

    private Player player;

    public Game(Player player) {

        this.player = player;

    }

    public String attack() {

        return "Player attack with: " + player.getWeapon();

    }

}

class Player {

    private String weapon;

    public Player(String weapon) {

        this.weapon = weapon;

    }

    String getWeapon() {

        return weapon;

    }

}

如您所见，Game类需要Player执行attack。

@RunWith(MockitoJUnitRunner.class)

class GameTest {

    @Mock

    Player player;

    @InjectMocks

    Game game;

    @Test

    public void attackWithSwordTest() throws Exception {

        Mockito.when(player.getWeapon()).thenReturn("Sword");

        assertEquals("Player attack with: Sword", game.attack());

    }

}

Mockito将模拟Player类，并使用when和thenReturn方法对其行为进行模拟。最后，使用@InjectMocksMockito将其Player放入Game。

注意，您甚至不必创建new Game对象。Mockito将为您注入。

// you don't have to do this

Game game = new Game(player);

使用@Spy注释，我们也会得到相同的行为。即使属性名称不同。

@RunWith(MockitoJUnitRunner.class)

public class GameTest {

  @Mock Player player;

  @Spy List<String> enemies = new ArrayList<>();

  @InjectMocks Game game;

  @Test public void attackWithSwordTest() throws Exception {

    Mockito.when(player.getWeapon()).thenReturn("Sword");

    enemies.add("Dragon");

    enemies.add("Orc");

    assertEquals(2, game.numberOfEnemies());

    assertEquals("Player attack with: Sword", game.attack());

  }

}

class Game {

  private Player player;

  private List<String> opponents;

  public Game(Player player, List<String> opponents) {

    this.player = player;

    this.opponents = opponents;

  }

  public int numberOfEnemies() {

    return opponents.size();

  }

  // ...

这是因为Mockito将检查Type SignatureGame类的Player和List<String>。