title: Gradle does not find my tests with Kotlin and JUnit 5
body: <p>I have written some basic unit tests with Kotlin and Junit 5. Unfortunately, when I run them from Intellij IDEA, the tests are not found by Gradle.
  I am getting the message "No tests found for given includes: [de.mhaug.phd.btcwallet.BasicTests]" from Gradle and the message "Test event not received" from Intellij. </p>
  
  <p>Interestingly, running it from the commandline with "./gradlew :clean :test" reports a successful build. However, my first test is obviously red, so this shows that Gradle did not execute it.</p>
  
  <p>I already tried running it with more verbose output but nothing helpful showed up. Here is a minimal (not) working example:</p>
  
  <pre><code>package de.mhaug.phd.btcwallet
  
  import org.junit.jupiter.api.Assertions.assertEquals
  import org.junit.jupiter.api.Assertions.assertFalse
  import org.junit.jupiter.api.Test
  
  class BasicTests {
    @Test
    fun hey() {
      assertEquals(3,1+1)
    }
  
    @Test
    fun hey2() {
      assertFalse(3==1+1)
    }
  }
  </code></pre>
  
  <p>This is my build.gradle:</p>
  
  <pre><code>buildscript {
      ext.kotlin_version = '1.2.10'
  
      repositories {
          mavenCentral()
      }
      dependencies {
          classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
      }
  }
  
  group 'de.mhaug.phd'
  version '1.0-SNAPSHOT'
  
  apply plugin: 'kotlin'
  
  repositories {
      mavenCentral()
  }
  
  dependencies {
      compile "org.jetbrains.kotlin:kotlin-stdlib-jdk8:$kotlin_version"
      compile group: 'org.bouncycastle', name: 'bcprov-jdk16', version: '1.46'
      testImplementation group: 'org.junit.jupiter', name: 'junit-jupiter-api', version: '5.0.2'
      testRuntimeOnly group: 'org.junit.jupiter', name: 'junit-jupiter-engine', version: '5.0.2'
  //    testCompile group: 'org.junit.platform', name: 'junit-platform-runner', version: ''
  //    testCompile group: 'org.junit.jupiter', name: 'junit-jupiter-params', version: '5.0.2'
  }
  
  compileKotlin {
      kotlinOptions.jvmTarget = "1.8"
  }
  compileTestKotlin {
      kotlinOptions.jvmTarget = "1.8"
  }
  </code></pre>
  
  <p>How can I make Intellij/Gradle execute my tests?</p>