在使用 Gradle 进行 build 的时候运行测试，提示 build 不能完成，测试不能进行。
错误信息：
Caused by: org.junit.platform.commons.PreconditionViolationException: Cannot create Launcher without at least one TestEngine; consider adding an engine implementation JAR to the classpath
org.gradle.api.internal.tasks.testing.TestSuiteExecutionException: Could not complete execution for Gradle Test Executor 19.
at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:63)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
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$DispatchingInvocationHandler.invoke(ProxyDispatchAdapter.java:94)
at com.sun.proxy.$Proxy2.stop(Unknown Source)
at org.gradle.api.internal.tasks.testing.worker.TestWorker.stop(TestWorker.java:132)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.base/java.lang.reflect.Method.invoke(Method.java:566)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:36)
at org.gradle.internal.dispatch.ReflectionDispatch.dispatch(ReflectionDispatch.java:24)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:182)
at org.gradle.internal.remote.internal.hub.MessageHubBackedObjectConnection$DispatchWrapper.dispatch(MessageHubBackedObjectConnection.java:164)
at org.gradle.internal.remote.internal.hub.MessageHub$Handler.run(MessageHub.java:412)
at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:64)
at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:48)
at java.base/java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1128)
at java.base/java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:628)
at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:56)
at java.base/java.lang.Thread.run(Thread.java:834)Caused by: org.junit.platform.commons.PreconditionViolationException: Cannot create Launcher without at least one TestEngine; consider adding an engine implementation JAR to the classpath
at org.junit.platform.commons.util.Preconditions.condition(Preconditions.java:296)
at org.junit.platform.launcher.core.DefaultLauncher.<init>(DefaultLauncher.java:58)
at org.junit.platform.launcher.core.LauncherFactory.create(LauncherFactory.java:91)
at org.junit.platform.launcher.core.LauncherFactory.create(LauncherFactory.java:67)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.processAllTestClasses(JUnitPlatformTestClassProcessor.java:97)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor$CollectAllTestClassesExecutor.access$000(JUnitPlatformTestClassProcessor.java:79)
at org.gradle.api.internal.tasks.testing.junitplatform.JUnitPlatformTestClassProcessor.stop(JUnitPlatformTestClassProcessor.java:75)
at org.gradle.api.internal.tasks.testing.SuiteTestClassProcessor.stop(SuiteTestClassProcessor.java:61)
... 25 moreWrap lines
这里有关 Junit 5 进行 Gradle 配置的时候需要配置测试引擎。
请参考下面的链接中的说明：
https://docs.gradle.org/current/userguide/java_testing.html#using_junit5
首先你需要在你的依赖中添加下面的内容：
testImplementation 'org.junit.jupiter:junit-jupiter-api:5.6.1'
testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.6.1'
同时，如果你使用的是 Junit 5 的话，你还需要指定测试：
test {
useJUnitPlatform()}
如果你这里不指定这个 test 测试的话，你项目的测试是不会运行的。