Inject the JUnit version to tests via system property

The sample now expects the JUnit version to be injected via a system
property. This will allow consistent upgrades of libraries without
having to update the samples themselves.

Author: melix

native-gradle-plugin/buildSrc/src/main/groovy/org.graalvm.build.functional-testing.gradle

@@ -79,6 +79,7 @@ configurations.functionalTestImplementation.extendsFrom(configurations.testImple
         inputs.files(files("src/samples"))
         inputs.files(configurations.functionalTestCommonRepository)
         systemProperty('common.repo.url', configurations.functionalTestCommonRepository.incoming.files.files[0])
+        systemProperty('versions.junit', project.properties.junit_jupiter_version)
         environment('GRAALVM_HOME', javaToolchains.launcherFor {
             languageVersion.set(JavaLanguageVersion.of(11))
             vendor.set(JvmVendorSpec.matching("GraalVM Community"))

native-gradle-plugin/src/functionalTest/groovy/org/graalvm/buildtools/gradle/JavaApplicationWithTestsFunctionalTest.groovy

@@ -41,8 +41,10 @@
 package org.graalvm.buildtools.gradle
 
 import org.graalvm.buildtools.gradle.fixtures.AbstractFunctionalTest
+import spock.lang.Unroll
 
 class JavaApplicationWithTestsFunctionalTest extends AbstractFunctionalTest {
+    @Unroll("can execute tests in a native image on Gradle #version with JUnit Platform #junitVersion")
     def "can execute tests in a native image"() {
         gradleVersion = version
         def nativeTestsApp = file("build/native/native-tests")
@@ -83,5 +85,6 @@ class JavaApplicationWithTestsFunctionalTest extends AbstractFunctionalTest {
 
         where:
         version << TESTED_GRADLE_VERSIONS
+        junitVersion = System.getProperty('versions.junit')
     }
 }

native-gradle-plugin/src/samples/java-application-with-tests/build.gradle

@@ -11,12 +11,16 @@ application {
     mainClass.set('org.graalvm.demo.Application')
 }
 
+def junitVersion = providers.systemProperty('versions.junit')
+    .forUseAtConfigurationTime()
+    .orElse('5.7.2') // so that the sample runs if someone checks it out without the testing infra
+    .get()
+
 dependencies {
-    testImplementation(platform('org.junit:junit-bom:5.7.2'))
+    testImplementation(platform("org.junit:junit-bom:${junitVersion}"))
     testImplementation('org.junit.jupiter:junit-jupiter')
 }
 
 test {
     useJUnitPlatform()
 }
-