模拟 Guava CacheLoader 回调方法

Question

我一直试图模拟回调，但没有成功。下面是一个示例代码：

public class TestService {
    private UtilService utilService;
    private LoadingCache<String, String> cache= CacheBuilder.newBuilder()
            .build(new CacheLoader<String, String>() {
                public String load(String key) throws Exception {
                    System.out.println("key = " + key);
                    return getKey(key);
                }
            });
    public String getkeyFromCache(String key) throws ExecutionException {
        return cache.get(key);
    }
    @VisibleForTesting
    public String getKey(String key) {
        return utilService.getKey(key);
    }
}

还有这样的测试用例：

@RunWith(MockitoJUnitRunner.class)
public class TestServiceTest {
    public static final String MYKEY = "Mykey";
    @Spy
    TestService testService=new TestService();
    @Before
    public void before() {
        MockitoAnnotations.initMocks(this);
    }
    @Test
    public void testCache() throws ExecutionException {
        doReturn(MYKEY).when(testService).getKey(MYKEY);
        String result=testService.getkeyFromCache(MYKEY);
        String result2nd=testService.getkeyFromCache(MYKEY);
        verify(testService,times(1)).getKey(MYKEY);
    }
}

但看起来它没有被调用

Wanted but not invoked:
testService.getKey("Mykey");
-> at utils.TestServiceTest.testCache(TestServiceTest.java:38)
However, there were other interactions with this mock:
-> at utils.TestServiceTest.testCache(TestServiceTest.java:36)
-> at utils.TestServiceTest.testCache(TestServiceTest.java:37)
    at utils.TestServiceTest.testCache(TestServiceTest.java:38)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:50)
    at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:12)
    at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:47)
    at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:17)
    at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:78)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:57)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:290)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:71)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:288)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:58)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:268)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.mockito.internal.runners.JUnit45AndHigherRunnerImpl.run(JUnit45AndHigherRunnerImpl.java:37)
    at org.mockito.runners.MockitoJUnitRunner.run(MockitoJUnitRunner.java:62)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:47)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)

我想测试缓存功能，而不是 UtilService 功能，所以我想模拟它。我想不出将答案或Captor用于此测试的方法，否则我会这样做。

Answer 1

您的问题是您自己创建了间谍。因此，回调将绑定到真正的方法。允许 Mockito 处理对象创建可以解决这个问题。（我正在使用模拟 1.10.19）

我已经重构了您的测试代码：

@RunWith(MockitoJUnitRunner.class)
public class TestServiceTest {
    public static final String MYKEY = "Mykey";
    @Spy
    TestService testService;
    @Test
    public void testCache() throws ExecutionException {
        doReturn(MYKEY).when(testService).getKey(MYKEY);
        String result=testService.getkeyFromCache(MYKEY);
        String result2nd=testService.getkeyFromCache(MYKEY);
        verify(testService).getKey(MYKEY);
    }
}

注意：由于您使用的是 Mockito 运行程序 - 您不需要自己初始化 Mockito。此外，times（1） 是用于验证调用的默认值。

Answer 2

当 getKey（） 方法在 load（） 方法内部调用时，它会在 TestService 类中调用，而不是通过模拟代理调用。这就是为什么

doReturn(MYKEY).when(testService).getKey(MYKEY);

不行。但是，您可以并且应该模拟UtilService，并看到它只被访问一次。