How to set different source / target versions for production code and test code

Introduction

In a Gradle Java project, the production code (Java code under the src / main / java directory) is equivalent to Java 7 equivalent compilation (when you specify the -source 1.7 -target 1.7 option with the javac command. ), But I want to compile the test code (Java code under src / test / java) equivalent to Java 8! In such a case, I didn't know how to specify sourceCompatibility or targetCompatibility in build.gradle, so I tried to verify it.

I didn't have to specify different source / target versions for production and test code, but JUnit 5 requires Java 8 at runtime It seems to be current / user-guide / # overview-java-versions), so it is necessary to compile with Java 7 on the production code side, but I want to use JUnit 5 for the test code! I think that you can refer to this setting in such cases.

How to set sourceCompatibility / targetCompatibility

As you can see in the build.gradle example below

--Production code settings --Specify normally --Test code settings --Specify in the properties of the compileTestJava task

If so, it's OK.

apply plugin: 'java'

//⭐️ source applied to production code/Target compatibility settings
sourceCompatibility = JavaVersion.VERSION_1_7
targetCompatibility = JavaVersion.VERSION_1_7

//⭐️ source that applies only to test code/Target compatibility settings
compileTestJava {
    sourceCompatibility = JavaVersion.VERSION_1_8
    targetCompatibility = JavaVersion.VERSION_1_8
}

//I tried using the sourceSets property as below, but this didn't work
//sourceSets {
//    main {
//        sourceCompatibility = JavaVersion.VERSION_1_7
//        targetCompatibility = JavaVersion.VERSION_1_7
//    }
//    test {
//        sourceCompatibility = JavaVersion.VERSION_1_8
//        targetCompatibility = JavaVersion.VERSION_1_8
//    }
//}

repositories {
    mavenCentral()
}

dependencies {
    // ...
}