使用Gradle与JUnit运行测试时遭遇ClassNotFoundException问题

我是Gradle新手，尝试一个简单的构建场景，项目目录结构如下：

│
└───src
    ├───main
    │   └───java
    │           ExampleApp.java
    │
    └───test
        └───java
                ExampleTest.java

使用的build.gradle.kts配置：

plugins {
    java
    id("jvm-test-suite")
}

repositories {
    mavenCentral()
}

tasks.named<Jar>("jar") {
    manifest {
        attributes["Main-Class"] = "ExampleApp"
    }
}

testing {
    suites { 
        val test by getting(JvmTestSuite::class) { 
            useJUnitJupiter() 
        }
    }
}

dependencies {
    testImplementation("org.junit.jupiter:junit-jupiter-api:5.9.0")
    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.9.0")
}

运行命令：

./gradlew clean test

测试任务失败，错误日志如下：

org.gradle.api.internal.tasks.testing.TestSuiteExecutionException: Could not execute test class 'ExampleTest'.
    at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:54)
    at java.base@21.0.1/jdk.internal.reflect.DirectMethodHandleAccessor.invoke(DirectMethodHandleAccessor.java:103)
    at java.base@21.0.1/java.lang.reflect.Method.invoke(Method.java:580)
    at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
    at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
    at org.gradle.internal.dispatch.ContextClassLoaderDispatch.dispatch(ContextClassLoaderDispatch.java:33)
    at org.gradle.internal.dispatch.ProxyDispatchAdapter$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
    at jdk.proxy1/jdk.proxy1.$Proxy2.processTestClass(Unknown Source)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker$2.run(TestWorker.java:176)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker.executeAndMaintainThreadName(TestWorker.java:129)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:100)
    at org.gradle.api.internal.tasks.testing.worker.TestWorker.execute(TestWorker.java:60)
    at org.gradle.process.internal.worker.child.ActionExecutionWorker.execute(ActionExecutionWorker.java:56)
    at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:113)
    at org.gradle.process.internal.worker.child.SystemApplicationClassLoaderWorker.call(SystemApplicationClassLoaderWorker.java:65)
    at app//worker.org.gradle.process.internal.worker.GradleWorkerMain.run(GradleWorkerMain.java:69)
    at app//worker.org.gradle.process.internal.worker.GradleWorkerMain.main(GradleWorkerMain.java:74)
Caused by: org.gradle.internal.UncheckedException: java.lang.ClassNotFoundException: ExampleTest
    at org.gradle.internal.UncheckedException.throwAsUncheckedException(UncheckedException.java:68)
    at org.gradle.internal.UncheckedException.throwAsUncheckedException(UncheckedException.java:41)
    at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.loadClass(JUnitPlatformTestClassProcessor.java:170)
    at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.access$100(JUnitPlatformTestClassProcessor.java:62)
    at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.execute(JUnitPlatformTestClassProcessor.java:104)
    at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.execute(JUnitPlatformTestClassProcessor.java:94)
    at org.gradle.api.internal.tasks.testing.junit.AbstractJUnitTestClassProcessor.processTestClass(AbstractJUnitTestClassProcessor.java:60)
    at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.processTestClass(SuiteTestClassProcessor.java:52)
    ... 16 more
Caused by: java.lang.ClassNotFoundException: ExampleTest
    at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641)
    at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:188)
    at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:526)
    at java.base/java.lang.Class.forName0(Native Method)
    at java.base/java.lang.Class.forName(Class.java:534)
    at java.base/java.lang.Class.forName(Class.java:513)
    at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.loadClass(JUnitPlatformTestClassProcessor.java:168)
    ... 21 more

生成的类文件目录结构显示测试类已编译：

│
├───build
│   ├───classes
│   │   └───java
│   │       ├───main
│   │       │       ExampleApp.class
│   │       │
│   │       └───test
│   │               ExampleTest.class

补充信息：

• 运行环境：Windows 11，JDK 21，Gradle 8.6
• 相同类和目录结构用Maven可正常运行，改用JUnit4也会报同样错误
• 克隆JUnit5官方示例项目测试，同样出现java.lang.ClassNotFoundException
• macOS环境下运行完全正常

解决方案 #

1. 临时禁用Gradle守护进程 #

运行测试时添加--no-daemon参数：

./gradlew clean test --no-daemon

2. 配置Gradle禁用IPv6优先 #

在项目根目录的gradle.properties文件中添加以下配置（如果没有该文件则新建）：

systemProp.java.net.preferIPv6Addresses=false

3. 检查项目路径 #

确保项目所在路径没有中文、空格或特殊字符，移到纯英文无空格的路径下再尝试构建。

4. 版本兼容调整 #

如果以上方法无效，尝试降级JDK版本到17（Gradle 8.6对JDK17的兼容性更稳定），或者降级Gradle版本到8.5。

内容的提问来源于stack exchange，提问作者Lionishy