从Android Studio 2.4迁移到3.0时的Robolectric NPE

Question

从Android Studio 2.4迁移到3.0时，Robolectric的大多数（也许全部）测试都会因下面的奇怪错误而失败。我们正在使用Robolectric 3.2.2。

java.lang.RuntimeException: java.lang.RuntimeException: java.lang.NullPointerException

    at org.robolectric.RobolectricTestRunner$2.evaluate(RobolectricTestRunner.java:332)
    at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:259)
    at org.robolectric.RobolectricTestRunner.runChild(RobolectricTestRunner.java:41)
    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.robolectric.RobolectricTestRunner$1.evaluate(RobolectricTestRunner.java:199)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:363)
    at org.junit.runner.JUnitCore.run(JUnitCore.java:137)
    at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68)
    at com.intellij.rt.execution.junit.IdeaTestRunner$Repeater.startRunnerWithArgs(IdeaTestRunner.java:51)
    at com.intellij.rt.execution.junit.JUnitStarter.prepareStreamsAndStart(JUnitStarter.java:242)
    at com.intellij.rt.execution.junit.JUnitStarter.main(JUnitStarter.java:70)
    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.AppMainV2.main(AppMainV2.java:131)
Caused by: java.lang.RuntimeException: java.lang.NullPointerException
    at org.robolectric.res.ResourceParser.load(ResourceParser.java:57)
    at org.robolectric.res.ResourceTableFactory.newResourceTable(ResourceTableFactory.java:21)
    at org.robolectric.res.ResourceMerger.buildResourceTable(ResourceMerger.java:22)
    at org.robolectric.RobolectricTestRunner.getAppResourceTable(RobolectricTestRunner.java:499)
    at org.robolectric.RobolectricTestRunner.access$600(RobolectricTestRunner.java:41)
    at org.robolectric.RobolectricTestRunner$2.evaluate(RobolectricTestRunner.java:327)
... 19 more
Caused by: java.lang.NullPointerException
    at org.robolectric.res.DocumentLoader.loadFile(DocumentLoader.java:39)
    at org.robolectric.res.DocumentLoader.load(DocumentLoader.java:30)
    at org.robolectric.res.ResourceParser.load(ResourceParser.java:21)
... 24 more

对于Robolectric，还没有为Android Studio 3.0提供支持吗？

更新

崩溃发生在Robolectric DocumentLoader类。

private void loadFile(FsFile dir, XmlLoader[] xmlLoaders) {
 if (!dir.exists()) {
  throw new RuntimeException("no such directory " + dir);
 }

 for (FsFile file : dir.listFiles(ENDS_WITH_XML)) {
  loadResourceXmlFile(file, xmlLoaders);
 }
}

当dir.listFiles(ENDS_WITH_XML)时，它返回Null。这就是崩溃的原因。也许在最新的Android Studio上，资源没有生成XML？

更新

找到这个公关。也许这会解决问题，因为当它为空时，dir不是目录。

https://github.com/robolectric/robolectric/pull/3158/files

更新

将问题报告给Robolectric https://github.com/robolectric/robolectric/issues/3216