To download and install JUnit you currently have the following options.

Download the following JARs and add them to your test classpath:

• junit.jar
• hamcrest-core.jar

Add a dependency to junit:junit in test scope. (Note: 4.13 is the latest stable version as of the latest edit on this page.)

<dependency>
  <groupId>junit</groupId>
  <artifactId>junit</artifactId>
  <version>4.13</version>
  <scope>test</scope>
</dependency>

See Use-with-Gradle