java - Future<T> 类型的 Mockito Mock 方法参数

Question

我有以下代码:

public final class JoinableTaskPool<T> extends ABC {

       public Future<T> submit(final Callable<T> task) {
           executorService.submit(new Runnable() {
             public void run() {
                try {
                    final Future<T> result = service.take();
                    try {
                        handler.processResult(result);
                    } catch (final Throwable t) {
                        throw new SearchException("Task has an error", t);
                    }
                } catch (InterruptedException e) {
                    throw new SearchException("Task has an error", e);
                }
            }
          } 
       }
  }

我正在尝试为此方法编写单元测试。方法如下:

@RunWith(MockitoJUnitRunner.class)
public class TestJoinableTaskPool<T> {

    private JoinableTaskPool<T> pool;

    @Before
    public void setUp() {
        pool = new JoinableTaskPool<T>(1);
    }

    @After
    public void tearDown() {
        pool.shutdown();
    }

    @Test
    public void testSubmit() throws Exception{
        Callable task = (Callable<T>) () -> null;
        Future<T> result = new FutureTask<T>(task);
        Mockito.when(pool.getCompService().take())
                .thenReturn(result);

        Mockito.when(pool.getFinishHandler().processResult(result))
                .thenThrow(RuntimeException.class);

        pool.submit(task);
    }
}

我在下面一行收到编译错误:

reason: no instance(s) of type variable(s) T exist so that void conforms to T

Mockito.when(pool.getFinishHandler().processResult(result))
                .thenThrow(RuntimeException.class);

我们如何解决这个问题？我尝试将 T 替换为 String 或任何其他类，但问题仍然存在。将 any() 作为参数传递给 processResult 现在也可以正常工作，我希望该方法调用抛出一个断言的异常。

如有任何帮助，我们将不胜感激。

Answer 1

您的测试类是通用的。您期望它的具体类型来自哪里？该消息已经告诉它:“no instance(s) of type variable(s) T exist ”。

如果我从 TestJoinableTaskPool 中删除类型参数并替换所有 <T>具有具体类型，例如Object ，Mockito抛出异常:

org.mockito.exceptions.misusing.MissingMethodInvocationException: 
when() requires an argument which has to be 'a method call on a mock'.
For example:
    when(mock.getArticles()).thenReturn(articles);

Also, this error might show up because:
1. you stub either of: final/private/equals()/hashCode() methods.
   Those methods *cannot* be stubbed/verified.
   Mocking methods declared on non-public parent classes is not supported.
2. inside when() you don't call method on mock but on some other object.

这是可以理解的，因为 .processResult(result)在 Handler 上调用但没有Handler mock 。