JUnit 5 has been designed to be forward and backward compatible. On the one hand, the Vintage component supports running legacy code on JUnit 3 and 4. On the other hand, JUnit 5 provides a JUnit 4 runner that allows to run JUnit 5 in IDEs and build systems that support JUnit 4, but does not yet support the new JUnit Platform 5 directly.

Let's see one example. Imagine we want to run a Jupiter test in an IDE does not support JUnit 5, for example, an old version of Eclipse. In this case, we need to annotate our Jupiter test with @RunWith(JUnitPlatform.class). The JUnitPlatform runner is a JUnit 4-based runner, which enables to run any test whose programming model is supported on the JUnit Platform in a JUnit 4 environment. Therefore, our test would result as follows:

package io.github.bonigarcia;

import static org.junit.jupiter.api.Assertions.assertEquals;

import org.junit.jupiter.api.Test;
import org.junit.platform.runner.JUnitPlatform;
import org.junit.runner.RunWith;

@RunWith(JUnitPlatform.class)
public class JUnit5CompatibleTest {

   @Test 
   void myTest() {
      String message = "1+1 should be equal to 2";
      System.out.println(message);
      assertEquals(2, 1 + 1, message);
   }

}

If this test is contained in a Maven project, our pom.xml should contain the following dependencies:

<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>
     <dependency>
        <groupId>org.junit.platform</groupId>
        <artifactId>junit-platform-runner</artifactId>
        <version>${junit.platform.version}</version>
        <scope>test</scope>
     </dependency>
 </dependencies>

On the other hand, for a Gradle project, our build.gradle is the following:

buildscript {
   repositories {
      mavenCentral()
   }
   dependencies {
      classpath("org.junit.platform:junit-platform-gradle-plugin:${junitPlatformVersion}")
   }
}

repositories {
   mavenCentral()
}

apply plugin: 'java'
apply plugin: 'eclipse'
apply plugin: 'idea'
apply plugin: 'org.junit.platform.gradle.plugin'

compileTestJava {
   sourceCompatibility = 1.8
   targetCompatibility = 1.8
   options.compilerArgs += '-parameters'
}

dependencies {
   testCompile("org.junit.jupiter:junit-jupiter-api:${junitJupiterVersion}")
   testRuntime("org.junit.jupiter:junit-jupiter-engine:${junitJupiterVersion}")
   testCompile("org.junit.platform:junit-platform-runner:${junitPlatformVersion}")
}