运行Cucumber测试时出现ExceptionInInitializerError问题求助

问题描述 #

运行Cucumber测试时触发初始化错误，使用的TestRunner代码如下：

package myTestRunner;

import org.junit.runner.RunWith;

import cucumber.api.CucumberOptions;
import cucumber.api.junit.Cucumber;

@RunWith(Cucumber.class)
@CucumberOptions(
    features="features",
    glue="stepDefinitions"
)
public class TestRunner {

}

执行后抛出如下异常：

java.lang.ExceptionInInitializerError
    at cucumber.deps.com.thoughtworks.xstream.XStream.setupConverters(XStream.java:820)
    at cucumber.deps.com.thoughtworks.xstream.XStream.<init>(XStream.java:574)
    at cucumber.deps.com.thoughtworks.xstream.XStream.<init>(XStream.java:530)
    at cucumber.runtime.xstream.LocalizedXStreams$LocalizedXStream.<init>(LocalizedXStreams.java:50)
    at cucumber.runtime.xstream.LocalizedXStreams.newXStream(LocalizedXStreams.java:37)
    at cucumber.runtime.xstream.LocalizedXStreams.get(LocalizedXStreams.java:29)
    at cucumber.runtime.StepDefinitionMatch.runStep(StepDefinitionMatch.java:37)
    at cucumber.runtime.Runtime.runStep(Runtime.java:300)
    at cucumber.runtime.model.StepContainer.runStep(StepContainer.java:44)
    at cucumber.runtime.model.StepContainer.runSteps(StepContainer.java:39)
    at cucumber.runtime.model.CucumberScenario.run(CucumberScenario.java:44)
    at cucumber.runtime.junit.ExecutionUnitRunner.run(ExecutionUnitRunner.java:102)
    at cucumber.runtime.junit.FeatureRunner.runChild(FeatureRunner.java:63)
    at cucumber.runtime.junit.FeatureRunner.runChild(FeatureRunner.java:18)
    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 cucumber.runtime.junit.FeatureRunner.run(FeatureRunner.java:70)
    at cucumber.api.junit.Cucumber.runChild(Cucumber.java:95)
    at cucumber.api.junit.Cucumber.runChild(Cucumber.java:38)
    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 cucumber.api.junit.Cucumber.run(Cucumber.java:100)
    at org.eclipse.jdt.internal.junit4.runner.JUnit4TestReference.run(JUnit4TestReference.java:93)
    at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:40)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:529)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:756)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:452)
    at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210)
    at ✽.Given Open the browser(MyAccount_Login.feature:6)
Caused by: java.lang.reflect.InaccessibleObjectException: Unable to make field private final java.util.Comparator java.util.TreeMap.comparator accessible: module java.base does not "opens java.util" to unnamed module @606d8acf
    at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:354)
    at java.base/java.lang.reflect.AccessibleObject.checkCanSetAccessible(AccessibleObject.java:297)
    at java.base/java.lang.reflect.Field.checkCanSetAccessible(Field.java:180)
    at java.base/java.lang.reflect.Field.setAccessible(Field.java:174)
    at cucumber.deps.com.thoughtworks.xstream.core.util.Fields.locate(Fields.java:39)
    at cucumber.deps.com.thoughtworks.xstream.converters.collections.TreeMapConverter.<clinit>(TreeMapConverter.java:50)
    ... 35 more

原因分析 #

这个错误的核心是Java 9+的模块化系统与旧版本Cucumber依赖的XStream版本不兼容：

• 旧版本Cucumber内嵌的XStream库会通过反射访问Java核心模块（java.base）中java.util.TreeMap的私有字段comparator；
• Java 9及以上引入的模块系统默认禁止非模块代码（无名模块）访问核心模块的内部私有成员，因此抛出InaccessibleObjectException，进而引发初始化异常ExceptionInInitializerError。

解决办法 #

1. 升级Cucumber版本（推荐方案） #

升级到支持Java 9+的Cucumber版本（4.8.0及以上，建议用最新稳定版），这些版本已修复XStream的兼容性问题，部分新版本甚至替换了XStream为其他序列化库。

如果使用Maven，替换原有依赖为：

<dependency>
    <groupId>io.cucumber</groupId>
    <artifactId>cucumber-java</artifactId>
    <version>7.14.0</version>
    <scope>test</scope>
</dependency>
<dependency>
    <groupId>io.cucumber</groupId>
    <artifactId>cucumber-junit</artifactId>
    <version>7.14.0</version>
    <scope>test</scope>
</dependency>

注意：旧版的cucumber.api包已废弃，需改用io.cucumber的groupId。

2. 添加JVM启动参数（临时 workaround） #

如果暂时无法升级Cucumber，可通过JVM参数允许无名模块访问java.base的java.util包：

--add-opens java.base/java.util=ALL-UNNAMED

在Eclipse中，可在Run Configuration的VM arguments中添加该参数。

3. 降级Java版本 #

若项目允许，将Java版本降级到Java 8，Java 8没有模块系统，不会存在此类权限限制问题。

内容的提问来源于stack exchange，提问作者Madhusudhan Vm