Junit测试使用Mockito的异步方法

Question

我在Java 1.8类中实现了使用Spring Framework（版本5.0.5.5.Release）中的异步方法：

public class ClassToBeTested {
    @Autowired
    private MyComponent myComponent;
    @Async
    public void doStuff(List<MyClass> myObjects) {
        CompletableFuture<MyResponseObject>[] futureList = new CompletableFuture[myObjects.size()];
        int count = 0;
        for (MyClass myObject : myObjects) {
            futureList[count] = myComponent.doOtherStuff(myObject);
            count++;
        }
        // Wait until all doOtherStuff() calls have been completed
        CompletableFuture.allOf(futureList).join();
        ... other stuff ...
    }
}

我正在尝试使用Junit和Mockito测试课程。我已经将其设置为如下，目的是嘲笑Dostuff（）方法对组件的调用：

@MockBean
private MyComponent myComponentAsAMock;
@InjectMocks
@Autowired
private ClassToBeTested classToBeTested;
@Test
public void myTest() throws Exception {
    // Create object to return when myComponent.doOtherStuff() is called.
    CompletableFuture<MyResponseObject> completableFuture = new CompletableFuture<MyResponseObject>();
    ... populate an instance of MyResponseObject ...
    completableFuture.complete(myResponseObject);
    // Return object when myComponent.doOtherStuff() is called.
    Mockito.when(
        myComponentAsAMock.doOtherStuff(ArgumentMatchers.any(MyClass.class)))
        .thenReturn(completableFuture);
    // Test.
    List<MyClass> myObjects = new ArrayList<MyClass>();
    MyClass myObject = new MyClass();
    myobjects.add(myObject);
    classToBeTested.doStuff(myObjects);
}

当我在Eclipse中单独运行时，单位测试似乎是成功的，但是对整个项目进行Maven构建，但我注意到正在投掷NullPoInterExceptions：

[ThreadExecutor2] .a.i.SimpleAsyncUncaughtExceptionHandler : Unexpected error occurred invoking async method 'public void package.ClassToBeTested.doStuff(java.util.List)'.
java.lang.NullPointerException: null
at java.util.concurrent.CompletableFuture.andTree(CompletableFuture.java:1306) ~[na:1.8.0_131]
at java.util.concurrent.CompletableFuture.allOf(CompletableFuture.java:2225) ~[na:1.8.0_131]
at package.ClassToBeTested.doStuff(ClassToBeTested.java:75) ~[classes/:na]

在这条classtobetested.java的行上提出了错误：

CompletableFuture.allOf(completedFutureList).join();

it 看起来像像测试完成后在Maven构建输出中显示的异常消息（还有其他测试正在运行其输出，其输出发生在显示错误消息之前），所以我``我猜这与dostuff（）的呼叫是异步的事实有关。

任何帮助将不胜感激。

Answer 1

解决方案是在暂停和检查中添加一个overito验证步骤，以确保模拟组件的方法称为适当的次数：

    Mockito.verify(myComponentAsAMock, Mockito.timeout(1000).times(1)).doOtherStuff(ArgumentMatchers.any(MyClass.class));