java - Mockito 如何捕获传递给注入(inject)的模拟对象方法的参数？

Question

我正在尝试测试一个内部使用 Spring AMQP 连接对象的服务类。这个连接对象是由 Spring 注入(inject)的。但是，我不希望我的单元测试实际与 AMQP 代理通信，所以我使用 Mockito 注入(inject)连接对象的模拟。

/** 
 * The real service class being tested.  Has an injected dependency. 
 */ 
public class UserService {

   @Autowired
   private AmqpTemplate amqpTemplate;

   public final String doSomething(final String inputString) {
      final String requestId = UUID.randomUUID().toString();
      final Message message = ...;
      amqpTemplate.send(requestId, message);
      return requestId;
   }
}

/** 
 * Unit test 
 */
public class UserServiceTest {

   /** This is the class whose real code I want to test */
   @InjectMocks
   private UserService userService;

   /** This is a dependency of the real class, that I wish to override with a mock */
   @Mock
   private AmqpTemplate amqpTemplateMock;

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

   @Test
   public void testDoSomething() {
      doNothing().when(amqpTemplateMock).send(anyString(), any(Message.class));

      // Call the real service class method, which internally will make 
      // use of the mock (I've verified that this works right).
      userService.doSomething(...);

      // Okay, now I need to verify that UUID string returned by 
      // "userService.doSomething(...) matches the argument that method 
      // internally passed to "amqpTemplateMock.send(...)".  Up here 
      // at the unit test level, how can I capture the arguments passed 
      // to that inject mock for comparison?
      //
      // Since the value being compared is a UUID string created 
      // internally within "userService", I cannot just verify against 
      // a fixed expected value.  The UUID will by definition always be
      // unique.
   }
}

此代码示例中的注释有望清楚地说明问题。当 Mockito 将模拟依赖注入(inject)到真实类中，并且对真实类的单元测试导致它调用模拟时，您以后如何检索传递给注入(inject)模拟的确切参数？

Answer 1

使用一个或多个ArgumentCaptor。

目前尚不清楚您的类型在这里，但无论如何。假设你有一个 mock，它有一个方法 doSomething() 以 Foo 作为参数，然后你这样做:

final ArgumentCaptor<Foo> captor = ArgumentCaptor.forClass(Foo.class);

verify(mock).doSomething(captor.capture());

final Foo argument = captor.getValue();

// Test the argument

此外，您的方法似乎返回 void 并且您不希望它执行任何操作。就这样写吧:

doNothing().when(theMock).doSomething(any());