尝试使用 PowerMockRunner 运行测试时出现 PowerMock ClassCastException

Question

只需将以下依赖项添加到我的 Android maven 项目中：

        <dependency>
            <groupId>org.powermock</groupId>
            <artifactId>powermock-module-junit4</artifactId>
            <version>${powermock.version}</version>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.powermock</groupId>
            <artifactId>powermock-api-mockito</artifactId>
            <version>${powermock.version}</version>
            <scope>test</scope>
        </dependency>

然后用 @RunsWith(PowerMockRunner.class) 注释类

在执行 mvn clean test 时，我得到了这个奇怪的类转换异常：

java.lang.ClassCastException: org.powermock.modules.junit4.internal.impl.PowerMockJUnit49RunnerDelegateImpl cannot be cast to org.powermock.modules.junit4.common.internal.PowerMockJUnitRunnerDelegate
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.createDelegatorFromClassloader(JUnit4TestSuiteChunkerImpl.java:143)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.createDelegatorFromClassloader(JUnit4TestSuiteChunkerImpl.java:39)
    at org.powermock.tests.utils.impl.AbstractTestSuiteChunkerImpl.createTestDelegators(AbstractTestSuiteChunkerImpl.java:217)
    at org.powermock.modules.junit4.common.internal.impl.JUnit4TestSuiteChunkerImpl.<init>(JUnit4TestSuiteChunkerImpl.java:59)
    at org.powermock.modules.junit4.common.internal.impl.AbstractCommonPowerMockRunner.<init>(AbstractCommonPowerMockRunner.java:32)
    at org.powermock.modules.junit4.PowerMockRunner.<init>(PowerMockRunner.java:33)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
    at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:39)
    at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:27)
    at java.lang.reflect.Constructor.newInstance(Constructor.java:513)
    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.apache.maven.surefire.junit4.JUnit4TestSet.<init>(JUnit4TestSet.java:45)
    at org.apache.maven.surefire.junit4.JUnit4DirectoryTestSuite.createTestSet(JUnit4DirectoryTestSuite.java:56)
    at org.apache.maven.surefire.suite.AbstractDirectoryTestSuite.locateTestSets(AbstractDirectoryTestSuite.java:96)
    at org.apache.maven.surefire.Surefire.createSuiteFromDefinition(Surefire.java:209)
    at org.apache.maven.surefire.Surefire.run(Surefire.java:156)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
    at java.lang.reflect.Method.invoke(Method.java:597)
    at org.apache.maven.surefire.booter.SurefireBooter.runSuitesInProcess(SurefireBooter.java:338)
    at org.apache.maven.surefire.booter.SurefireBooter.main(SurefireBooter.java:997)

我发现这是由于在同一个测试项目中使用了 robolectric 测试运行器。但它不适用于相同的测试。我的意思是，有一个带有@RunsWith(RobolectricTestRunner.class) 的类和一个带有@RunsWith(PowerMockTestRunner.class) 的新类。删除所有使用 Robolectric 注释的类时，它可以工作。

知道为什么会发生这种情况吗？

提前致谢

Answer 1

Robolectric 和 PowerMock 仪器代码都通过自定义类加载器。一些可能的解决方法：

1. 为 PowerMock 测试创建一个新的 Maven 子模块。

2. 我尚未对此进行测试，但您可以使用 annotation @PowerMockIgnore 使其工作。

3. surefire 插件中的Change the fork mode 到pertest。我没有尝试过，因为它可能会减慢测试速度。