Spek + JUnit5 config for Android project

ExampleSpekTest

import org.jetbrains.spek.api.Spek
import org.jetbrains.spek.api.dsl.given
import org.jetbrains.spek.api.dsl.it
import org.junit.Assert

class ExampleSpekTest : Spek({
    val x = 2
    val y = 3

    given("x = $x and y = $y") {
        val sum = x + y

        it("should be that x + y = 5") {
            (x + y) shouldEqual sum
        }

        it("should be that x - y = -1") {
            val subtract = x - y
            (x - y) shouldEqual substract
        }
    }
})

module's build.gradle

apply plugin: 'com.android.application'
apply plugin: 'kotlin-android'
apply plugin: 'kotlin-android-extensions'
apply plugin: "de.mannodermaus.android-junit5"

android {
    compileSdkVersion 26
    defaultConfig {
        applicationId "x.x.x"
        minSdkVersion 27
        targetSdkVersion 26
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }
    sourceSets {
        test.java.srcDirs += 'src/test/kotlin'
        androidTest.java.srcDirs += 'src/androidTest/kotlin'
    }
}

project.ext {
    buildToolsVersion = "26.1.0"
    constraintLayoutVersion = "1.0.2"
    spekVersion = "1.1.5"
    mockitoKotlinVersion = "2.0.0-alpha02"
    kluentVersion = "1.34"
}

android.testOptions {
    junitPlatform {
        filters {
            engines {
                include 'spek'
            }
        }
    }
}

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    implementation"org.jetbrains.kotlin:kotlin-stdlib-jre7:$kotlin_version"
    implementation 'com.android.support:appcompat-v7:$buildToolsVersion'
    implementation 'com.android.support.constraint:constraint-layout:$constraintLayoutVersion'
    //
    // TESTS
    testImplementation("org.jetbrains.spek:spek-api:$spekVersion") {
        exclude group: "org.jetbrains.kotlin"
    }
    testImplementation("org.jetbrains.spek:spek-junit-platform-engine:$spekVersion") {
        exclude group: "org.junit.platform"
        exclude group: "org.jetbrains.kotlin"
    }
    testImplementation "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"

    testImplementation junit5.unitTests()
    testCompileOnly junit5.unitTestsRuntime()
}

project's build.gradle

buildscript {
    ext.kotlin_version = '1.2.10'
    repositories {
        google()
        jcenter()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:3.0.1'
        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
        classpath "de.mannodermaus.gradle.plugins:android-junit5:1.0.30"

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        google()
        jcenter()
    }
}

task clean(type: Delete) {
    delete rootProject.buildDir
}