java - Mockito Spy 看不到正确的原始值

Question

我面临以下问题，当间接更新 spy 对象的字段时， spy 看不到 primitive 字段的更新，而它看到的是 reference一次。

举个例子:

import org.junit.Test;
import org.mockito.Mockito;

import java.util.function.Consumer;
import java.util.concurrent.atomic.AtomicBoolean;

public class MyTest {

    class Actor {
        Consumer<Boolean> consumer;

        void init(Consumer<Boolean> consumer){
            this.consumer = consumer;
        }

        void act(boolean flag){
            this.consumer.apply(flag);
        }
    }

    class TestClass {
        boolean field = true;
        AtomicBoolean refField = new AtomicBoolean(true);

        TestClass(Actor actor){
           actor.init( flag -> {
               System.out.println("Changing field to " + flag);
               field = flag;
               refField.set(flag);
           });
        }

        void call(){
            this.doSomething(field);
        }
   
        void callRef(){
            this.doSomething(refField.get());
        }

        void doSomething(boolean flag){
            System.out.println("#doSomething(" + flag + ")");
        }
    }

    @Test
    public void test(){
        // given an actor and a spied TestClass
        Actor actor = new Actor();
        TestClass spy = Mockito.spy(new TestClass(actor));

        // when invoking the action with the primitive
        spy.call();
        // then expect correct invocation
        Mockito.verify(spy, Mockito.times(1)).doSomething( true );

       // when invoking the action with the ref field
       spy.callRef();
       // then expect correct invocation
       Mockito.verify(spy, Mockito.times(2)).doSomething( true );

       // when changing the flag to 'false'
       actor.act( false );

       // and invoking the action with the refField
       spy.callRef();
       // then expect correct invocation
       Mockito.verify(spy, Mockito.times(1)).doSomething(false);

      // when invoking the action with the primitive
      spy.call();
      // then method is NOT invoked as expected !!!!!!!
      Mockito.verify(spy, Mockito.times(2)).doSomething(false);
    }
}

最后一次验证将失败，因为该方法是用第一个原始值调用的。

我想知道为什么会这样？这是预期的行为吗？运行上述测试，将产生以下日志记录:

#doSomething(true)
#doSomething(true)
Changing flag to false
#doSomething(false)
#doSomething(true)

我希望最后一条日志语句以 false 调用。

对以上内容有什么见解吗？

PS: Version=mockito-core:2.25.0

Answer 1

您的系统中有 2 个 TestClass 对象实例:

• 原始实例
• spy 实例

spy 是从原始实例创建的。

• 原始字段(如 boolean 字段)被复制，每个 TestClass 都包含
• 引用被复制，但底层引用对象是共享的(refField)

让我们进行以下更改以观察:

TestClass(Actor actor){
    actor.init( flag -> {
        // print referenced TestClass instance 
        System.out.println("from actor: " + TestClass.this);
        System.out.println("Changing field to " + flag);
        field = flag;
        refField.set(flag);
    });
}

@Test
public void test(){
    // given an actor and a spied TestClass
    Actor actor = new Actor();
    TestClass testClassOriginal = new TestClass(actor);
    TestClass spy = Mockito.spy(testClassOriginal);
    System.out.println("org" + testClassOriginal);
    System.out.println("spy" + spy);
  
    // when changing the flag to 'false'
    actor.act( false );
    System.out.println("After change org: " + testClassOriginal.field);
    System.out.println("After change spy: " + spy.field);
}

给出以下输出:

org: mypackage.MyTest$TestClass@4218500f
spy: mypackage.MyTest$TestClass$MockitoMock$2115616475@5c10f1c3
from actor: mypackage.MyTest$TestClass@4218500f
Changing field to false
After change org: false
After change spy: true

可以清楚的看到:

• TestClass 的两个实例
• Actor 看到的是原始对象，而不是 spy
• 当 actor 对原始字段进行更改时，它会更改原始字段
• spy 中的原始字段保持不变

可能的解决方案

你需要让 Actor 看到 spy ，而不是原来的对象。为此，必须将 TestClass 的创建与注册消费者分离。

class TestClass {
    boolean field = true;
    AtomicBoolean refField = new AtomicBoolean(true);

    TestClass(){
    }

    void consumeFlag(Boolean flag) {
        System.out.println("from actor: " + this);
        System.out.println("Changing field to " + flag);
        field = flag;
        refField.set(flag);
    }
    // ...
}

@Test
public void test(){
    // given an actor and a spied TestClass
    Actor actor = new Actor();
    TestClass spy = Mockito.spy(new TestClass());
    actor.init(spy::consumeFlag);
    // ...
}