Java Spring JUnit5でNoClassDefFoundErrorが発生

JUnit5でNoClassDefFoundError:が発生

Junit5を実行すると以下のエラーが発生した。

java.lang.NoClassDefFoundError: org/junit/platform/engine/EngineDiscoveryListener
	at java.base/java.lang.ClassLoader.defineClass1(Native Method)
	at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
	at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:174)
	at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:802)
	at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:700)
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:623)
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
	at org.junit.platform.launcher.core.LauncherDiscoveryRequestBuilder.getLauncherDiscoveryListener(LauncherDiscoveryRequestBuilder.java:241)
	at org.junit.platform.launcher.core.LauncherDiscoveryRequestBuilder.build(LauncherDiscoveryRequestBuilder.java:235)
	at org.eclipse.jdt.internal.junit5.runner.JUnit5TestLoader.createUnfilteredTest(JUnit5TestLoader.java:75)
	at org.eclipse.jdt.internal.junit5.runner.JUnit5TestLoader.createTest(JUnit5TestLoader.java:66)
	at org.eclipse.jdt.internal.junit5.runner.JUnit5TestLoader.loadTests(JUnit5TestLoader.java:53)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:526)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:770)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:464)
	at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:210)
Caused by: java.lang.ClassNotFoundException: org.junit.platform.engine.EngineDiscoveryListener
	at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:583)
	at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
	at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
	... 18 more

解決方法

gradleの場合は、「build.gradle」の「dependencies」に以下依存関係を追加。その後、プロジェクト上で右クリック、「Gradle」→「Refresh Gradle Project」を実行で解決しました。

testRuntimeOnly 'org.junit.platform:junit-platform-launcher'

Mavenの書き方はMavenリポジトリのURL先を参照してください。「https://mvnrepository.com/artifact/org.junit.platform/junit-platform-launcher」