Robolectric 启动期间反射出现 NullPointerException - 有任何提示吗？

我正在 Eclipse 上开发一个 Android 项目，并且我正在尝试从在模拟器/设备上运行测试（即very慢）到机器人电动.

我用 Robolectric 替换了 Android 库，将 JUnit 添加到路径中，将测试用例改回常规TestCase并添加了建议的@RunWith(RobolectricTestRunner.class)来自快速入门指南（进行必要的更改来实例化我的 Activity，而不是依赖 Android 的 Activity 测试来为我完成此操作）。

但是，当我运行测试时，我得到：

java.lang.NullPointerException
 at com.xtremelabs.robolectric.RobolectricTestRunner.isInstrumented(RobolectricTestRunner.java:123)
 at com.xtremelabs.robolectric.RobolectricTestRunner.<init>(RobolectricTestRunner.java:72)
 at com.xtremelabs.robolectric.RobolectricTestRunner.<init>(RobolectricTestRunner.java:57)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
 at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:57)
 at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
 at java.lang.reflect.Constructor.newInstance(Constructor.java:532)
 at org.junit.internal.builders.AnnotatedBuilder.buildRunner(AnnotatedBuilder.java:31)
 at org.junit.internal.builders.AnnotatedBuilder.runnerForClass(AnnotatedBuilder.java:24)
 at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
 at org.junit.internal.builders.AllDefaultPossibilitiesBuilder.runnerForClass(AllDefaultPossibilitiesBuilder.java:29)
 at org.junit.runners.model.RunnerBuilder.safeRunnerForClass(RunnerBuilder.java:57)
 at org.junit.internal.requests.ClassRequest.getRunner(ClassRequest.java:24)
 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.<init>(JUnit4TestReference.java:29)
 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestClassReference.<init>(JUnit4TestClassReference.java:25)
 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.createTest(JUnit4TestLoader.java:40)
 at org.eclipse.jdt.internal.junit4.runner.JUnit4TestLoader.loadTests(JUnit4TestLoader.java:30)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:452)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
 at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)

这似乎与这段代码有关（0.9 标签起，因为 0.9.1 标签没有它）RobolectricTestRunner.java:

private static boolean isInstrumented() {
    return RobolectricTestRunner.class.getClassLoader().getClass().getName().contains(RobolectricClassLoader.class.getName());
}

但我不明白如何实现，因为这种反射应该在类本身中起作用。

另外，我可以发誓它在重复失败之前运行过一次 - 我已经删除了 robolectric 缓存（按照建议here）并用最新的（4.8.2）替换了 Eclipse 的 JUnit，但没有任何改变。

有什么提示吗？

UPDATE:我尝试创建一个新的 Java（即普通的非 Android）测试项目，正如快速入门指南中所述。但是，现在测试运行抱怨没有 AndroidManifest.xml：

java.lang.RuntimeException: java.io.FileNotFoundException: /Users/chester/Documents/workspace/minitruco-android/minitruco-android-robolectric-test/AndroidManifest.xml (No such file or directory)
    at com.xtremelabs.robolectric.RobolectricTestRunner.createResourceLoader(RobolectricTestRunner.java:245)
    at com.xtremelabs.robolectric.RobolectricTestRunner.setupApplicationState(RobolectricTestRunner.java:215)
    at com.xtremelabs.robolectric.RobolectricTestRunner.internalBeforeTest(RobolectricTestRunner.java:163)
    at com.xtremelabs.robolectric.RobolectricTestRunner.methodBlock(RobolectricTestRunner.java:143)
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.io.FileNotFoundException: /Users/chester/Documents/workspace/minitruco-android/minitruco-android-robolectric-test/AndroidManifest.xml (No such file or directory)
    at java.io.FileInputStream.open(Native Method)
    at java.io.FileInputStream.<init>(FileInputStream.java:137)
    at java.io.FileInputStream.<init>(FileInputStream.java:96)
    at sun.net.www.protocol.file.FileURLConnection.connect(FileURLConnection.java:87)
    at sun.net.www.protocol.file.FileURLConnection.getInputStream(FileURLConnection.java:178)
    at com.sun.org.apache.xerces.internal.impl.XMLEntityManager.setupCurrentEntity(Unknown Source)
    at com.sun.org.apache.xerces.internal.impl.XMLVersionDetector.determineDocVersion(Unknown Source)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
    at com.sun.org.apache.xerces.internal.parsers.XML11Configuration.parse(Unknown Source)
    at com.sun.org.apache.xerces.internal.parsers.XMLParser.parse(Unknown Source)
    at com.sun.org.apache.xerces.internal.parsers.DOMParser.parse(Unknown Source)
    at com.sun.org.apache.xerces.internal.jaxp.DocumentBuilderImpl.parse(Unknown Source)
    at javax.xml.parsers.DocumentBuilder.parse(Unknown Source)
    at com.xtremelabs.robolectric.RobolectricTestRunner.findResourcePackageName(RobolectricTestRunner.java:255)
    at com.xtremelabs.robolectric.RobolectricTestRunner.createResourceLoader(RobolectricTestRunner.java:236)
    ... 18 more

我猜想测试应该从原始项目 (minitruco-android) 加载文件，该文件显示在测试项目的构建路径和 Eclipse 上的运行/调试构建配置中（在测试项目的类路径条目下）。无论如何，我已经从原始测试项目中复制了该文件（只是为了测试），但随后它抱怨 R.java （并且that确实应该从原始项目导入）：

java.lang.RuntimeException: java.lang.ClassNotFoundException: caught an exception while obtaining a class file for me.chester.minitruco.test.R
    at com.xtremelabs.robolectric.RobolectricTestRunner.createResourceLoader(RobolectricTestRunner.java:245)
    at com.xtremelabs.robolectric.RobolectricTestRunner.setupApplicationState(RobolectricTestRunner.java:215)
    at com.xtremelabs.robolectric.RobolectricTestRunner.internalBeforeTest(RobolectricTestRunner.java:163)
    at com.xtremelabs.robolectric.RobolectricTestRunner.methodBlock(RobolectricTestRunner.java:143)
    at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
    at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
    at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
    at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
    at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
    at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
    at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
    at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:46)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:467)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:683)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:390)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:197)
Caused by: java.lang.ClassNotFoundException: caught an exception while obtaining a class file for me.chester.minitruco.test.R
    at javassist.Loader.findClass(Loader.java:359)
    at com.xtremelabs.robolectric.RobolectricClassLoader.findClass(RobolectricClassLoader.java:60)
    at javassist.Loader.loadClass(Loader.java:311)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:268)
    at com.xtremelabs.robolectric.RobolectricClassLoader.loadClass(RobolectricClassLoader.java:37)
    at java.lang.ClassLoader.loadClassInternal(ClassLoader.java:336)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:186)
    at com.xtremelabs.robolectric.RobolectricTestRunner.createResourceLoader(RobolectricTestRunner.java:237)
    ... 18 more
Caused by: javassist.NotFoundException: me.chester.minitruco.test.R
    at javassist.ClassPool.get(ClassPool.java:436)
    at com.xtremelabs.robolectric.AndroidTranslator.onLoad(AndroidTranslator.java:68)
    at javassist.Loader.findClass(Loader.java:340)
    ... 26 more

我的设置和快速启动之间唯一不同的是，我在测试项目上保留测试源，在常规项目上保留常规源（自从第一个构建以来，我假设测试项目看到常规源 - 其中，当然，这在很大程度上取决于）。

我在用着SoyLatte，但也尝试了 Mac OS 的默认 1.6 JVM，得到了相同的结果。

谢谢。

我们过去也遇到过同样的问题。对我们有用的是扩展RobolectricTestRunner并为其提供一个机器人配置知道我们项目位置的实例。这样我就不必用 eclipse 修改任何运行配置，它就可以工作了。

    package ...;

    import java.io.File;

    import org.junit.runners.model.InitializationError;

    import com.xtremelabs.robolectric.RobolectricConfig;
    import com.xtremelabs.robolectric.RobolectricTestRunner;

    public class TestRunner extends RobolectricTestRunner {

        public static final string MAIN_PROJECT_PATH = "../path_to_android_project";

        public TestRunner(Class<?> testClass) throws InitializationError {
             super(testClass, new RobolectricConfig(new File(MAIN_PROJECT_PATH)));
        }
    }