how to enable assertions through the Gradle Kotlin DSL?

Question

The simplest possible assert usage I could think of:

thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ 
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ ls
App.java
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ 
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ cat App.java 



public class App {

    public String getGreeting() {
        boolean foo = false;
        assert foo;
        return "Hello world.";
    }

    public static void main(String[] args) {
        System.out.println(new App().getGreeting());
    }
}

thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ 
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ javac App.java
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ 
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ ls
App.class  App.java
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ 
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ java App
Hello world.
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ 
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ java -ea App
Exception in thread "main" java.lang.AssertionError
    at App.getGreeting(App.java:10)
    at App.main(App.java:15)
thufir@dur:~/NetBeansProjects/helloAssertions/src/main/java$ 

Which is fine, so far as it goes. How would I modify the build file:

/*
 * This file was generated by the Gradle 'init' task.
 *
 * This generated file contains a sample Java project to get you started.
 * For more details take a look at the Java Quickstart chapter in the Gradle
 * user guide available at https://docs.gradle.org/5.0/userguide/tutorial_java_projects.html
 */

plugins {
    // Apply the java plugin to add support for Java
    java

    // Apply the application plugin to add support for building an application
    application
}

repositories {
    // Use jcenter for resolving your dependencies.
    // You can declare any Maven/Ivy/file repository here.
    jcenter()
}

dependencies {
    // This dependency is found on compile classpath of this component and consumers.
    implementation("com.google.guava:guava:26.0-jre")

    // Use TestNG framework, also requires calling test.useTestNG() below
    testImplementation("org.testng:testng:6.14.3")
}

application {
    // Define the main class for the application
    mainClassName = "App"
}

val test by tasks.getting(Test::class) {
    // Use TestNG for unit tests
    useTestNG()
}

so that it will run with assertions enabled?

Answer 1

You must enable assertions via the -ea flag.

application {
    // Define the main class for the application
    mainClassName = "App"
    // enable assertions
    applicationDefaultJvmArgs = ['-ea']
}