java 没有至少一个 TestEngine 就无法创建 Launcher；考虑将引擎实现 JAR 添加到 Junit 5 中的类路径
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Cannot create Launcher without at least one TestEngine; consider adding an engine implementation JAR to the classpath in Junit 5
提问by Bhuwan Prasad Upadhyay
I got following execption when i tried to run test case in junit5:
当我尝试在 junit5 中运行测试用例时，我得到了以下执行：
Failed to execute goal org.apache.maven.plugins:maven-surefire-plugin:2.19:test (default-test) on project CRUD-App: Execution default-test of goal org.apache.maven.plugins:maven-surefire-plugin:2.19:test failed: There was an error in the forked process
org.junit.platform.commons.util.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:161)
at org.junit.platform.launcher.core.DefaultLauncher.<init>(DefaultLauncher.java:52)
at org.junit.platform.launcher.core.LauncherFactory.create(LauncherFactory.java:42)
at org.junit.platform.surefire.provider.JUnitPlatformProvider.invoke(JUnitPlatformProvider.java:59)
at org.apache.maven.surefire.booter.ForkedBooter.invokeProviderInSameClassLoader(ForkedBooter.java:286)
at org.apache.maven.surefire.booter.ForkedBooter.runSuitesInProcess(ForkedBooter.java:240)
at org.apache.maven.surefire.booter.ForkedBooter.main(ForkedBooter.java:121)
pom.xml
pom.xml
<dependencies>
...
<dependency>
<groupId>org.junit</groupId>
<artifactId>junit5-api</artifactId>
<version>5.0.0-SNAPSHOT</version>
<scope>test</scope>
</dependency>
</dependencies>
<build>
<plugins>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19</version>
<dependencies>
<dependency>
<groupId>org.junit.platform</groupId>
<artifactId>junit-platform-surefire-provider</artifactId>
<version>1.0.0-M2</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
Test Class:
测试类：
public class PersonServiceTest {
final Database database = Database.from("jdbc:h2:mem:" + App.DB_NAME);
final PersonService personService = new PersonService(database);
public PersonServiceTest() {
}
@Test
@DisplayName("@Person#insert()")
public void testInsert() {
personService.insert(new PersonBuilder()
.setId(1).setName("Bhuwan")
.setAddress("KTM")
.setContactNo("984849").createPerson()
);
}
}
Maven Goal:mvn test
马文目标：mvn test
回答by Sam Brannen
For starters, you are mixing ALPHAsnapshot artifacts (i.e., org.junit:junit5-api:5.0.0-SNAPSHOT) with M2artifacts (i.e., org.junit.platform:junit-platform-surefire-provider:1.0.0-M2), which will never work.
首先，您将ALPHA快照工件（即org.junit:junit5-api:5.0.0-SNAPSHOT）与M2工件（即org.junit.platform:junit-platform-surefire-provider:1.0.0-M2）混合在一起，这将永远不会起作用。
The Mavensection in the user guide suggests to check out the pom.xmlfrom the junit5-maven-consumerproject. If you follow that example, you will end up with something like the following.
在Maven的用户手册中的部分建议对检查出pom.xml从junit5-Maven的消费项目。如果你按照那个例子，你最终会得到类似下面的东西。
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<java.version>1.8</java.version>
<junit.jupiter.version>5.0.0-M2</junit.jupiter.version>
<junit.platform.version>1.0.0-M2</junit.platform.version>
</properties>
<build>
<plugins>
<plugin>
<artifactId>maven-compiler-plugin</artifactId>
<version>3.1</version>
<configuration>
<source>${java.version}</source>
<target>${java.version}</target>
</configuration>
</plugin>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19</version>
<dependencies>
<dependency>
<groupId>org.junit.platform</groupId>
<artifactId>junit-platform-surefire-provider</artifactId>
<version>${junit.platform.version}</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>${junit.jupiter.version}</version>
<scope>test</scope>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>${junit.jupiter.version}</version>
<scope>test</scope>
</dependency>
</dependencies>
To writeyour tests, you only need the junit-jupiter-api; however, in order to runyour tests you must have a TestEngineon the classpath. For JUnit Jupiter you therefore need junit-jupiter-engineon the classpath as well.
要编写测试，您只需要junit-jupiter-api; 但是，为了运行您的测试，您必须TestEngine在类路径上有一个。因此，对于 JUnit Jupiter，您还需要junit-jupiter-engine在类路径上。
As Nicolai Parlog pointed out, you could add junit-jupiter-engineas a dependency for the maven-surefire-plugin; however, that would not include the JupiterTestEnginein the classpath for your IDE.
正如 Nicolai Parlog 指出的那样，您可以添加junit-jupiter-engine为maven-surefire-plugin; 但是，这不会JupiterTestEngine在您的 IDE 的类路径中包含。
If you're only running tests via Maven or with a recent beta version of IntelliJ 2016 (which has built-in support for JUnit 5), then you may not care if JupiterTestEngineis on the classpath in your IDE. But... if you're using Eclipse, NetBeans, or a non-beta version of IntelliJ, you'll definitely want the JupiterTestEngineon the classpath in the IDE as well.
如果您仅通过 Maven 或使用 IntelliJ 2016 的最新测试版（内置对 JUnit 5 的支持）运行测试，那么您可能不关心是否JupiterTestEngine在 IDE 的类路径中。但是……如果您使用的是 Eclipse、NetBeans 或 IntelliJ 的非测试版，您肯定也希望JupiterTestEngine在 IDE 的类路径中使用 。
Regards,
问候，
Sam (core JUnit 5 committer)
Sam（核心 JUnit 5 提交者）
回答by Nicolai
The Maven Surefire plugin not only needs the JUnit 5 provider but also a TestEngineimplementation to run tests with. To quote the JUnit 5 docs:
Maven Surefire 插件不仅需要 JUnit 5 提供程序，还需要一个TestEngine用于运行测试的实现。引用JUnit 5 文档：
In order to have Maven Surefire run any tests at all, a
TestEngineimplementation must be added to the runtime classpath.
为了让 Maven Surefire 运行任何测试，
TestEngine必须在运行时类路径中添加一个实现。
In accordance with that the following works:
据此，以下工作：
<build>
<plugins>
<plugin>
<artifactId>maven-surefire-plugin</artifactId>
<version>2.19</version>
<dependencies>
<dependency>
<groupId>org.junit.platform</groupId>
<artifactId>junit-platform-surefire-provider</artifactId>
<version>1.0.0-M4</version>
</dependency>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-engine</artifactId>
<version>5.0.0-M4</version>
</dependency>
</dependencies>
</plugin>
</plugins>
</build>
<dependencies>
<dependency>
<groupId>org.junit.jupiter</groupId>
<artifactId>junit-jupiter-api</artifactId>
<version>5.0.0-M4</version>
<scope>test</scope>
</dependency>
</dependencies>
Note that this configuration makes the engine a dependency of the surefire plugin, notof your test code.
请注意，此配置使引擎成为 surefire 插件的依赖项，而不是测试代码的依赖项。
回答by FabianoLothor
I solve it changing
我解决它改变
classpath "org.springframework.boot:spring-boot-gradle-plugin:2.1.8.RELEASE"
classpath "org.springframework.boot:spring-boot-gradle-plugin:2.1.8.RELEASE"
to
到
classpath "org.springframework.boot:spring-boot-gradle-plugin:2.2.0.RELEASE"
classpath "org.springframework.boot:spring-boot-gradle-plugin:2.2.0.RELEASE"
