Cannot create Launcher without at least one TestEngine; consider adding an engine implementation JAR to the classpath in Junit 5

Question

I got following execption when i tried to run test case in junit5:

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

<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:

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

Answer 1

Mixing ALPHA snapshot artifacts (i.e., org.junit:junit5-api:5.0.0-SNAPSHOT) with M2 artifacts (i.e., org.junit.platform:junit-platform-surefire-provider:1.0.0-M2), won't work.

The Maven section in the user guide suggests to check out the pom.xml from the junit5-maven-consumer project. If you follow that example, you will end up with something like the following.

<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 write your tests, you only need the junit-jupiter-api; however, in order to run your tests you must have a TestEngine on the classpath. For JUnit Jupiter you therefore need junit-jupiter-engine on the classpath as well.

As Nicolai Parlog pointed out, you could add junit-jupiter-engine as a dependency for the maven-surefire-plugin; however, that would not include the JupiterTestEngine in the classpath for your IDE.

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 JupiterTestEngine is 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 JupiterTestEngine on the classpath in the IDE as well.

Regards,

Sam (core JUnit 5 committer)