运行时JUnit测试中的Kotlin类上的NoClassDefFoundError

我的Kotlin类编译和运行在模拟器上没有问题。 但是,当我测试它,Android Studio说没有找到类。

这里是Kotlin类和使用它的例子:

// Product.kt data class Product( val id: Int, val name: String, val manufacturer: String) // MainActivity.java public class MainActivity extends Activity { @Override protected void onCreate(Bundle savedInstanceState) { super.onCreate(savedInstanceState); setContentView(R.layout.activity_main); Product product = new Product(0, "foo", "bar"); TextView textView = findViewById(R.id.textView); textView.setText(product.getName()); } } 

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但是当我为Kotlin类写一个JUnit测试时:

 // ProductTest.java public class ProductTest { @Test public void getName() throws Exception { Product p = new Product(0, "foo", "bar"); assertThat(p.getName(), equalTo("foo")); } } 

Android Studio编译代码,但拒绝运行测试:

 java.lang.NoClassDefFoundError: com/example/Product at com.example.ProductTest.getName(ProductTest.java:15) 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.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$2.evaluate(ParentRunner.java:268) at org.junit.runners.ParentRunner.run(ParentRunner.java:363) at org.junit.runner.JUnitCore.run(JUnitCore.java:137) at com.intellij.junit4.JUnit4IdeaTestRunner.startRunnerWithArgs(JUnit4IdeaTestRunner.java:68) at com.intellij.rt.execution.junit.IdeaTestRunner$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.ClassNotFoundException: com.example.Product at java.net.URLClassLoader.findClass(URLClassLoader.java:381) at java.lang.ClassLoader.loadClass(ClassLoader.java:424) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:331) at java.lang.ClassLoader.loadClass(ClassLoader.java:357) ... 28 more 

这里是模块级build.gradledependencies部分:

 dependencies { compile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" testCompile "org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version" testCompile "org.jetbrains.kotlin:kotlin-test:$kotlin_version" testCompile "org.jetbrains.kotlin:kotlin-test-junit:$kotlin_version" testCompile 'junit:junit:4.12' } 

我做错了什么?

目前这不适用于最新的工具。 Jetbrains跟踪器中存在一个悬而未决的问题 。

解决方案是在模块build.gradle文件中创建一个新的任务。

 android { task copyTestClasses(type: Copy) { from "build/tmp/kotlin-classes/debugUnitTest" into "build/intermediates/classes/debug" } 

然后将该任务添加到测试运行配置的“启动之前”部分。

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这是一个公开的问题,我猜这个问题很快就会解决:

https://youtrack.jetbrains.com/issue/KT-17951

https://issuetracker.google.com/issues/38454212

同时,您可以使用以下解决方法:

 task copyTestClasses(type: Copy) { from "build/tmp/kotlin-classes/debugUnitTest" into "build/intermediates/classes/debug" } task copySdkClasses(type: Copy) { from "build/tmp/kotlin-classes/debug" into "build/intermediates/classes/debug" } 

将它添加到你的Gradle文件(在android {…}部分之后)

之后,打开你的测试配置,并添加新的“启动前”步骤,将执行这些任务:

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有人确认这个bug已经在Android Studio 3 Canary 3中修复: https : //issuetracker.google.com/issues/38454212