Remove JavaExec-based tasks, migrate to native Gradle API (#101)

* Remove custom test tasks & move to configuration of existing unit tests instead
* Finished migration of test code to the native test tasks
* Remove more unnecessary stuff
* Update to Kotlin 1.2.51
* Migrate from old DSL (junit-platform-gradle-plugin) to native DSL for tag & engine declarations
* Remove custom dependency handlers & other hand-holding techniques for backwards compatibility
* Remove deprecated junit-platform-gradle-plugin from project

Author: Marcel Schnelle

android-junit5-embedded-runtime/LICENSE

@@ -7,7 +7,6 @@ apply plugin: "java-library"
 apply plugin: "idea"
 apply plugin: "jacoco"
 apply plugin: "kotlin"
-apply plugin: "org.junit.platform.gradle.plugin"
 
 // ------------------------------------------------------------------------------------------------
 // Compilation Tweaks
@@ -47,20 +46,16 @@ processTestResources {
 
 test {
   failFast = true
+  useJUnitPlatform()
   testLogging {
     events "passed", "skipped", "failed"
     exceptionFormat = "full"
   }
-}
 
-junitPlatform {
-  details "tree"
-  enableStandardTestTask true
+  // Enable this line to run slow Functional Tests on the local device as well
+  environment("CI", "true")
 }
 
-// Enable this line to run slow Functional Tests on the local device as well
-//junitPlatformTest.environment("CI", "true")
-
 dependencies {
   // Test Plugin Dependencies
   testImplementation project(":android-junit5")
@@ -108,5 +103,5 @@ task writeFunctionalTestCompileClasspath(type: WriteClasspathResource) {
 
 tasks.withType(WriteClasspathResource).all {
   processTestResources.finalizedBy it
-  junitPlatformTest.mustRunAfter it
+  test.mustRunAfter it
 }