JUnit 5 Gradle Example

In this JUnit 5 Gradle example, we will learn how to get the required dependencies for writing JUnit 5 tests with Gradle. Also, we will learn how to configure the JUnit Gradle plugin to run the tests.

Required dependencies

First, to be able to write JUnit 5 tests we need the junit-jupiter artifact as a dependency in build.gradle:

dependencies {
    testImplementation("org.junit.jupiter:junit-jupiter:5.8.0")
}

Now all we need is to tell to use the JUnit platform in the tests:

test {
    useJUnitPlatform()
}

Now we have the most basic setup for writing and running JUnit 5 tests with Gradle.

Configuration for Older Versions

Beginning from JUnit Jupiter 5.4.0 there is now an aggregator artifact junit-jupiter that transitively pulls in dependencies on junit-jupiter-api, junit-jupiter-params, and junit-jupiter-engine for simplified dependency management. This means that we don’t need additional dependencies to be able to write parameterized tests.

To be able to write JUnit 5 tests using an older version we need the junit-jupiter-api artifact as a dependency. We also need the JUnit Jupiter test engine in the test runtime classpath:

dependencies {
    testImplementation("org.junit.jupiter:junit-jupiter-api:5.3.2")
    testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.3.2")    
}

Beginning from Gradle 4.6 there is now native support for JUnit Jupiter. When using Gradle 4.5 or older, to be able to run JUnit 5 tests we have to configure the JUnit Gradle plugin:

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'org.junit.platform:junit-platform-gradle-plugin:1.3.2'
    }
}

apply plugin: 'org.junit.platform.gradle.plugin'

Now we have the setup for writing and running JUnit 5 tests with older versions of Gradle.

Running tests

The JUnit Gradle plugin discovers tests under src/test/java directory by default.

Let’s check if our configuration works by adding a very simple test that does nothing:

class GradleExampleTest {

    @Test
    void shouldRun() {

    }
}

Now we can run our tests on the command line with:

$ gradle test

We should see output similar to this:

:test
BUILD SUCCESSFUL in 2s

There we go! JUnit Gradle plugin is now running our tests.

Summary

In this JUnit 5 Gradle example we have learned how to add the required dependency for writing JUnit 5 tests and how to configure JUnit Gradle plugin to be able to run the tests.

The example code for this guide can be found on GitHub.