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PowerMockito .when().thenReturn() 与 randomUUID 不返回预期值[重复]

2024-01-01

我正在尝试测试一个连接到包含 JCR 节点的 SQL Server 数据库的 Web 服务方法，因为我们使用的是 JackRabbit。

该方法如下所示：

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;
}

Where jsonResult是一个与此类似的对象：

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

现在，当我尝试按照中的步骤测试它时这个答案 https://stackoverflow.com/a/36331711/2180785和代码这个帖子 https://blog.jayway.com/2014/11/29/using-another-junit-runner-with-powermock/我得到了以下代码（正如我所说，它是基于过去的链接）：

@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，当我测试此方法时，它给出了以下结果：

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}>

正如您所看到的，两个 UUID 都是不同的，从我在这个问题的第一个链接上读到的内容来看，每次静态方法都应该返回相同的 UUIDUUID.randomUUID()被称为（存储在uuid里面的变量TestJackRabbitService班级...

我也尝试过doReturn方法如所解释的这个答案 https://stackoverflow.com/a/38681915/2180785但它会产生以下堆栈跟踪：

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)

From 这个答案 https://stackoverflow.com/a/31417676/2180785我读到（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？我在测试类的一开始就注入依赖项，我真的很陌生JUnit测试和英语不是我的母语，但是我可以理解大部分内容，但这个答案让我很难理解它（由于我缺乏 JUnit 测试知识）。

我怎样才能让我的JUnit测试检索方法内生成的相同 ID（或拦截对UUID.randomUUD()返回 my 内的值JUnit test) ?

Edit

在尝试了@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}>

模拟系统类的常见错误是将它们添加到@PrepareForTest，但不幸的是，不可能直接模拟最终的 Java System 类。但PowerMock提供了解决方法 https://blog.jayway.com/2009/05/17/mocking-static-methods-in-java-system-classes/。 PowerMock 通过调用 PowerMock 类来替换对系统类的调用。应添加使用最终系统类的类@PrepareForTest

我已经添加example https://github.com/powermock/powermock-examples-maven/blob/master/system-classes/src/test/java/example/powermock/systemclasess/service/DocumentServiceTest.java如何模拟 UUID。

public class DocumentService {

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

Test

@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);
  }
}

您可能会发现更多内容文档 https://github.com/powermock/powermock/wiki/Mock-System.

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