由于NoClassDefFoundError:TestEngine，Junit 5测试无法在Eclipse中启动

(There was no question for this problem in stackoverflow, so I decided to share question & solution here.)I wanted to migrate my Spring Boot project from JUnit 4 to JUnit 5, so I added the new API as dependency and removed the old the ones: <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-test</artifactId> <scope>test</scope> <exclusions> <exclusion> <groupId>junit</groupId> <artifactId>junit</artifactId> </exclusion> </exclusions> </dependency> <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-api</artifactId> </dependency>I wanted to do a full migration of my project, so I explicitly excluded everything from JUnit 4, and also did not include the junit-vintage-engine (as recommended in the official migration guide).Then, I did the various changes to make the tests compile, like replacing @Before with @BeforeEach and organizing imports. All in all, this was pretty straightforward.But running the tests in Eclipse caused some trouble:First I got the message "Cannot find 'junit.framework.TestCase' on project build path. JUnit 3 tests can only be run if JUnit is on the build path." In the launch configuration dialog that popped up automatically, I was able to spot my mistake: I needed to select the 'Test runner' JUnit 5.Still no success. Now I got the message "No tests found with test runner 'JUnit 5'. This was confusing, because I had used the correct JUnit 5 annotations on the test methods. Eclipse even confirmed this because the launch configuration 'Test method' search listed the test methods just fine.After I while, I figured out that the test execution had printed a stack trace in the console:java.lang.NoClassDefFoundError: org/junit/platform/engine/TestEngine at org.junit.platform.launcher.core.ServiceLoaderTestEngineRegistry.loadTestEngines(ServiceLoaderTestEngineRegistry.java:35) at org.junit.platform.launcher.core.LauncherFactory.create(LauncherFactory.java:87) at org.junit.platform.launcher.core.LauncherFactory.create(LauncherFactory.java:67) at org.eclipse.jdt.internal.junit5.runner.JUnit5TestLoader.<init>(JUnit5TestLoader.java:34) at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method) at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62) at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45) at java.lang.reflect.Constructor.newInstance(Constructor.java:423) at java.lang.Class.newInstance(Class.java:456) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.createRawTestLoader(RemoteTestRunner.java:370) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.createLoader(RemoteTestRunner.java:365) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.defaultInit(RemoteTestRunner.java:309) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.init(RemoteTestRunner.java:224) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:208)Caused by: java.lang.ClassNotFoundException: org.junit.platform.engine.TestEngine at java.net.URLClassLoader.findClass(URLClassLoader.java:444) at java.lang.ClassLoader.loadClass(ClassLoader.java:486) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:378) at java.lang.ClassLoader.loadClass(ClassLoader.java:419) ... 14 moreThis pointed me to the root cause of the problem (see answer below)... 解决方案 The problem was that I was missing the dependency to the engine library: <dependency> <groupId>org.junit.jupiter</groupId> <artifactId>junit-jupiter-engine</artifactId> </dependency>Then, the tests run like a charm in Eclipse.Migration blogs like https://dev.to/martinbelev/how-to-enable-junit-5-in-new-spring-boot-project-29a8 do mention this dependency, but I primarily worked with the JUnit 5 documentation, and somehow I must have overlooked this important piece of information there... 这篇关于由于NoClassDefFoundError:TestEngine，Junit 5测试无法在Eclipse中启动的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持！ 上岸，阿里云！