java.lang.IllegalStateException : the temporary folder has not yet been created

Question

我正在为我的用例创建一个新的@Rule，它看起来像

public class ActiveDirectoryConfigurationRule extends ExternalResource {

  @Rule
  public TemporaryFolder temporaryFolder = new TemporaryFolder();

  public File addActiveDirectoryConfigurationToFile(ActiveDirectoryConfiguration configuration) throws IOException {
    File file = temporaryFolder.newFile();
    objectMapper.writeValue(file, configuration);
    return file;
  }

  private ObjectMapper registerJdk8ModuleAndGetObjectMapper() {
    ObjectMapper objectMapper = new ObjectMapper();
    objectMapper.registerModule(new Jdk8Module());
    return objectMapper;
  }
}

在我的测试中，我将其用作

public class ActiveDirectoryConfigurationStoreTest {

      @Rule
      public ActiveDirectoryConfigurationRule configurationRule = new ActiveDirectoryConfigurationRule();

          @Test
          public void getWhenConfigurationExists() throws Exception {
            ActiveDirectoryConfiguration activeDirectoryConfiguration = //....;
            File configurationToFile = configurationRule.addActiveDirectoryConfigurationToFile(activeDirectoryConfiguration);

            ActiveDirectoryConfigurationStore configurationStore = new ActiveDirectoryConfigurationStore(configurationToFile);
            Optional<ActiveDirectoryConfiguration> mayBeConfiguration = configurationStore.getConfiguration();
            assertTrue(mayBeConfiguration.isPresent());
          }
        }

当我运行此测试时，出现错误

java.lang.IllegalStateException: the temporary folder has not yet been created

    at org.junit.rules.TemporaryFolder.getRoot(TemporaryFolder.java:145)
    at org.junit.rules.TemporaryFolder.newFile(TemporaryFolder.java:78)
    at com.conf.store.ActiveDirectoryConfigurationRule.addActiveDirectoryConfigurationToFile(ActiveDirectoryConfigurationRule.java:48)
    at com.conf.store.ActiveDirectoryConfigurationStoreTest.getWhenConfigurationExists(ActiveDirectoryConfigurationStoreTest.java:25)
    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.rules.ExternalResource$1.evaluate(ExternalResource.java:48)
    at org.junit.rules.RunRules.evaluate(RunRules.java:20)
    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.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:119)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:42)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:234)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:74)
    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 com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)

似乎在创建自己的@Rule时，我无法依赖任何现有的@Rule

是这个问题吗？我该如何解决这个问题？

Answer 1

是的，我认为 JUnit 中没有内置任何东西可以让您像现在一样“嵌套”@Rule 对象。

我认为最明显的选择是:

1. 在您的自定义 @Rule 中，在适当的时间调用您的子 @Rule 上的各种方法。 (本质上，假设您是 JUnit 库，在每个接口(interface)上使用 @Rule。)我还没有深入研究细节来了解它有多复杂。
2. 让您的 @Rule 扩展 TemporaryFolder 而不是 ExternalResource，并确保在您要重写的任何方法中调用 super() 。这可以让你做“TemporaryFolder 所做的一切，然后做一些”，这可能不是完美的 OO 理论(因为它不是真正的 TemporaryFolder 类型)，但应该按照你想要的方式工作为了。我在设置需要使用特定环境进行测试的特定文件夹时使用了这种方法，并且效果相当好。
3. 让您的自定义 @Rule 将 TemporaryFolder 引用作为构造函数参数，然后将其保存在字段中并根据需要使用。这要求 @Rule 的所有用户都包含两个 @Rule 对象，但也许可以清楚地表明测试确实需要一个临时文件夹来完成其工作以及您的特定自定义设置。