PowerMockito .when().thenReturn(),randomUUID未返回预期值

Question

我想测试它连接到包含JCR节点,我们使用JackRabbit用一个SQL Server数据库的Web服务方法.

该方法如下:

public String addDocumentByJson(String fileName, byte[] fileContent, int status, String userName, String jsonProperties) {
    UUID id = UUID.randomUUID();
    // It does a bunch of operations here
    return jsonResult;
}

jsonResult与此类似的对象在哪里:

{
    "id" : "<A random UUID>"
    "version" : 1
}

现在,当我尝试测试它下面的步骤这个答案在和代码这个职位和我来到了用下面的代码(这是我说的是基于过去的链接):

@PrepareForTest({ UUID.class })
@RunWith(PowerMockRunner.class)
@PowerMockRunnerDelegate(SpringJUnit4ClassRunner.class)
@ContextConfiguration("/TestSpringConfig.xml")
public class TestJackRabbitService {

    @Autowired
    @Qualifier("jackRabbitService")
    IJackRabbitService jackRabbitService;

    private byte[] fileContent;
    private int versionFile;

    public TestJackRabbitService() {
        classLoader = getClass().getClassLoader();
    }
    @BeforeClass
    public static void init() {
        LOG.trace("Run @BeforeClass");
        try {
            fileContent = IOUtils.toByteArray(new FileInputStream(new File(Thread.currentThread().getContextClassLoader().getResource("fileTest.txt"))));
        } catch (Exception e) {
            LOG.error(ExceptionUtils.getStackTrace(e));
        }
    }

    @Before
    public void before() {
        LOG.trace("Run @Before");
        try {
            versionFile = jackRabbitService.getLastVersionOf(nameApp, nameFile); //This method returns an int,
        } catch (Exception e) {
            LOG.error(ExceptionUtils.getStackTrace(e));
        }
    }

    @Test
    public void testAddDocumentsByJson() {
        //Some tests which run correctly

        final UUID uuid = UUID.randomUUID();
        mockStatic(UUID.class);
        LOG.debug(uuid);
        //doReturn(uuid).when(UUID.randomUUID());
        when(UUID.randomUUID()).thenReturn(uuid);
        idFile = uuid;

        assertEquals(jackRabbitService.addDocumentByJson(nameFile, bytes, nameApp, 5, jsonproperties), "{\"id\":\"" + uuid + "\",\"version\":1}");
    }
}

但是,当我测试这个方法时,它给了我以下结果:

Results :

Failed tests: 
    testAddDocumentsByJson(com.optimissa.test.junit.TestJackRabbitService): expected:<{"id":"[1efaf3b8-ca7c-4e6f-878f-102d9a7a92d9]","version":1}> but was:<{"id":"[cfa1a8b0-be6a-46b1-90f5-d2f6d230796a]","version":1}>

正如你可以同时看到的UUID是不同的,从我对这个问题我的第一个链接阅读是,它应该返回相同的UUID每次静态方法UUID.randomUUID()被调用(在一个存储在uuid里面的变量TestJackRabbitService类...

我也尝试了本答案中doReturn解释的方法,但它产生了以下堆栈跟踪:

testAddDocumentsByJson(com.optimissa.test.junit.TestJackRabbitService)  Time elapsed: 5.279 sec  <<< ERROR!
org.mockito.exceptions.misusing.UnfinishedStubbingException: 
Unfinished stubbing detected here:
-> at com.optimissa.test.junit.TestJackRabbitService.testAddDocumentsByJson(TestJackRabbitService.java:143)

E.g. thenReturn() may be missing.
Examples of correct stubbing:
    when(mock.isOk()).thenReturn(true);
    when(mock.isOk()).thenThrow(exception);
    doThrow(exception).when(mock).someVoidMethod();
Hints:
 1. missing thenReturn()
 2. you are trying to stub a final method, which is not supported
 3: you are stubbing the behaviour of another mock inside before 'thenReturn' instruction if completed

    at org.powermock.core.MockGateway.doMethodCall(MockGateway.java:182)
    at org.powermock.core.MockGateway.doMethodCall(MockGateway.java:164)
    at org.powermock.core.MockGateway.methodCall(MockGateway.java:134)
    at com.optimissa.test.junit.TestJackRabbitService.testAddDocumentsByJson(TestJackRabbitService.java:143)
    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.springframework.test.context.junit4.statements.RunBeforeTestMethodCallbacks.evaluate(RunBeforeTestMethodCallbacks.java:75)
    at org.springframework.test.context.junit4.statements.RunAfterTestMethodCallbacks.evaluate(RunAfterTestMethodCallbacks.java:86)
    at org.springframework.test.context.junit4.statements.SpringRepeat.evaluate(SpringRepeat.java:84)
    at org.junit.runners.ParentRunner.runLeaf(ParentRunner.java:325)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:252)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.runChild(SpringJUnit4ClassRunner.java:94)
    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.internal.runners.statements.RunBefores.evaluate(RunBefores.java:26)
    at org.springframework.test.context.junit4.statements.RunBeforeTestClassCallbacks.evaluate(RunBeforeTestClassCallbacks.java:61)
    at org.springframework.test.context.junit4.statements.RunAfterTestClassCallbacks.evaluate(RunAfterTestClassCallbacks.java:70)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.springframework.test.context.junit4.SpringJUnit4ClassRunner.run(SpringJUnit4ClassRunner.java:191)
    at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner$2.call(DelegatingPowerMockRunner.java:149)
    at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner$2.call(DelegatingPowerMockRunner.java:141)
    at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner.withContextClassLoader(DelegatingPowerMockRunner.java:132)
    at org.powermock.modules.junit4.internal.impl.DelegatingPowerMockRunner.run(DelegatingPowerMockRunner.java:141)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.run(JUnit4TestSuiteChunkerImpl.java:121)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.run(AbstractCommonPowerMockRunner.java:57)
    at org.powermock.modules.junit4.PowerMockRunner.run(PowerMockRunner.java:59)
    at org.apache.maven.surefire.junit4.JUnit4Provider.execute(JUnit4Provider.java:252)
    at org.apache.maven.surefire.junit4.JUnit4Provider.executeTestSet(JUnit4Provider.java:141)
    at org.apache.maven.surefire.junit4.JUnit4Provider.invoke(JUnit4Provider.java:112)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at org.apache.maven.surefire.util.ReflectionUtils.invokeMethodWithArray(ReflectionUtils.java:189)
    at org.apache.maven.surefire.booter.ProviderFactory$ProviderProxy.invoke(ProviderFactory.java:165)
    at org.apache.maven.surefire.booter.ProviderFactory.invokeProvider(ProviderFactory.java:85)
    at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:115)
    at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:75)

从这个答案我读(但我不明白),也许我需要从我试图测试的类创建一个新对象？我在测试课的最开始注入依赖项,我真的很擅长JUnit测试,英语不是我的母语,但是我能理解大部分内容但是答案让我很难理解它(到期我在JUnit测试中缺乏知识).

如何进行JUnit测试以检索在方法内生成的相同ID(或拦截调用UUID.randomUUD()以返回JUnit测试中的值)？

---

编辑

在尝试@ hammerfest的答案后,进行了以下更改:

UUID uuid = PowerMockito.mock(UUID.class);

mockStatic(UUID.class);
when(UUID.randomUUID()).thenReturn(uuid);

String jsonToCompare = "{\"id\":\"" + uuid + "\",\"version\":1}";
String jsonFromJRS = jackRabbitService.addDocumentByJson(nameFile, bytes, nameApp, 5, jsonproperties);

assertEquals(jsonFromJRS, jsonToCompare);

我仍然得到这个结果:

testAddDocumentsByJson(com.optimissa.test.junit.TestJackRabbitService): expected:<{"id":"[493410b3-dd0b-4b78-97bf-289f50f6e74f]","version":1}> but was:<{"id":"[00000000-0000-0000-0000-000000000000]","version":1}>

Answer 1

@PrepareForTest模拟系统类的常见错误是它们被添加到了,但不幸的是,直接模拟最终的Java System类是不可能的.但PowerMock提供了解决方法.PowerMock通过调用PowerMock类替换对系统类的调用.应该添加使用最终系统类的类@PrepareForTest

我添加了如何模拟UUID的示例.

public class DocumentService {

  public JsonDocument saveDocument(JsonDocument document){
    UUID uuid = UUID.randomUUID();
    document.setId(uuid.toString());
    return document;
  }
}

测试

@RunWith(PowerMockRunner.class)
@PrepareForTest(DocumentService.class)
public class DocumentServiceTest {
@Test
public void should_set_id() throws Exception {
    final String id = "493410b3-dd0b-4b78-97bf-289f50f6e74f";
    UUID uuid = UUID.fromString(id);

    mockStatic(UUID.class);
    when(UUID.randomUUID()).thenReturn(uuid);

    DocumentService documentService = new DocumentService();

    JsonDocument document = new JsonDocument();
    documentService.saveDocument(document);

    assertThat(document.getId())
        .as("Id is set")
        .isEqualTo(id);
  }
}

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