AnnotationTests.kt

package edu.ucsd.dylukes.covenant

import edu.ucsd.dylukes.covenant.annotations.Requires
import org.junit.jupiter.api.Test
import org.junit.jupiter.api.assertThrows
import java.lang.RuntimeException

@Requires("n >= 0")
fun repeatChar(n: Int, c: Char = 'x') {
    var s = ""
    for (i in 1..n) {
        s += c
    }
}

class AnnotationTests {
    @Test
    fun `Simple annotations work`() {
        assertThrows<RuntimeException> {
            repeatChar(-1)
        }
    }
}

build.gradle

plugins {
    id 'org.jetbrains.kotlin.jvm' version '1.3.31'
    id 'org.jetbrains.kotlin.kapt' version '1.3.31'
}

allprojects {
    apply plugin: 'kotlin'

    group 'edu.ucsd.dylukes'
    version '1.0-SNAPSHOT'

    repositories {
        mavenCentral()
    }

    dependencies {
        implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk8"
    }

    compileKotlin {
        kotlinOptions.jvmTarget = "1.8"
    }

    compileTestKotlin {
        kotlinOptions.jvmTarget = "1.8"
    }
}

ContractAnnotationProcessor.kt

package edu.ucsd.dylukes.covenant

import javax.annotation.processing.*
import javax.lang.model.SourceVersion
import javax.lang.model.element.TypeElement

@MustBeDocumented
@Target(
    AnnotationTarget.FUNCTION,
    AnnotationTarget.CONSTRUCTOR,
    AnnotationTarget.PROPERTY_GETTER,
    AnnotationTarget.PROPERTY_SETTER
)
@Retention(AnnotationRetention.RUNTIME)
annotation class Requires(vararg val predicates: String)

@MustBeDocumented
@Target(
    AnnotationTarget.FUNCTION,
    AnnotationTarget.CONSTRUCTOR,
    AnnotationTarget.PROPERTY_GETTER,
    AnnotationTarget.PROPERTY_SETTER
)
@Retention(AnnotationRetention.RUNTIME)
annotation class Ensures(vararg val predicates: String)

@MustBeDocumented
@Target(AnnotationTarget.CLASS)
@Retention(AnnotationRetention.RUNTIME)
annotation class Invariant(vararg val predicates: String)

@SupportedSourceVersion(SourceVersion.RELEASE_8)
@SupportedAnnotationTypes(
    "edu.ucsd.dylukes.covenant.Requires",
    "edu.ucsd.dylukes.covenant.Ensures",
    "edu.ucsd.dylukes.covenant.Invariant"
)
class ContractAnnotationProcessor : AbstractProcessor() {
    override fun init(processingEnv: ProcessingEnvironment?) {
        super.init(processingEnv)
        println("HELLO WORLD")
    }

    override fun process(annotations: MutableSet<out TypeElement>?, roundEnv: RoundEnvironment?): Boolean {
        TODO("not implemented") //To change body of created functions use File | Settings | File Templates.
    }
}

core-build.gradle

// empty currently

test-build.gradle

apply plugin: 'kotlin-kapt'

dependencies {
    testImplementation project(':core')
    kaptTest project(':core')

    testImplementation "org.junit.jupiter:junit-jupiter-api:5.5.0-M1"
    testRuntime "org.junit.jupiter:junit-jupiter-engine:5.5.0-M1"
}

tasks {
    test {
        useJUnitPlatform()
    }
}

kapt {
    includeCompileClasspath = false
}