Provision the correct JDK for test tasks (#48561)

This PR adds build configuration to use the `jdk-download` plugin with
unit tests when no runtime java is configured externally.

It's a first part in a longer chain of changes described in #40531.

build.gradle

@@ -41,6 +41,7 @@ plugins {
 apply plugin: 'nebula.info-scm'
 apply from: 'gradle/build-scan.gradle'
 apply from: 'gradle/build-complete.gradle'
+apply from: 'gradle/runtime-jdk-provision.gradle'
 
 // common maven publishing configuration
 allprojects {

buildSrc/src/main/groovy/org/elasticsearch/gradle/BuildPlugin.groovy

@@ -661,7 +661,6 @@ class BuildPlugin implements Plugin<Project> {
                 test.jvmArgumentProviders.add(nonInputProperties)
                 test.extensions.add('nonInputProperties', nonInputProperties)
 
-                test.executable = "${BuildParams.runtimeJavaHome}/bin/java"
                 test.workingDir = project.file("${project.buildDir}/testrun/${test.name}")
                 test.maxParallelForks = System.getProperty('tests.jvms', BuildParams.defaultParallel.toString()) as Integer
 

buildSrc/src/main/java/org/elasticsearch/gradle/Jdk.java

@@ -111,6 +111,15 @@ public class Jdk implements Buildable, Iterable<File> {
         return configuration.getBuildDependencies();
     }
 
+    public Object getBinJavaPath() {
+        return new Object() {
+            @Override
+            public String toString() {
+                return getPath() + "/bin/java";
+            }
+        };
+    }
+
     // internal, make this jdks configuration unmodifiable
     void finalizeValues() {
         if (version.isPresent() == false) {

buildSrc/src/main/java/org/elasticsearch/gradle/JdkDownloadPlugin.java

@@ -173,7 +173,8 @@ public class JdkDownloadPlugin implements Plugin<Project> {
             jdkConfig = configurations.create(remoteConfigName);
             configurations.create(localConfigName);
         }
-        String platformDep = platform.equals("darwin") ? (vendor.equals("adoptopenjdk") ? "mac" : "osx") : platform;
+        String platformDep = platform.equals("darwin") || platform.equals("osx") ?
+            (vendor.equals("adoptopenjdk") ? "mac" : "osx") : platform;
         String extension = platform.equals("windows") ? "zip" : "tar.gz";
         String jdkDep = vendor + ":" + platformDep + ":" + jdkVersion + "@" + extension;
         rootProject.getDependencies().add(configName(vendor, version, platform), jdkDep);

buildSrc/src/minimumRuntime/java/org/elasticsearch/gradle/VersionProperties.java

@@ -25,7 +25,8 @@ public class VersionProperties {
 
     public static String getBundledJdk(final String platform) {
         switch (platform) {
-            case "darwin":
+            case "darwin": // fall trough
+            case "mac":
                 return bundledJdkDarwin;
             case "linux":
                 return bundledJdkLinux;

gradle/runtime-jdk-provision.gradle

@@ -0,0 +1,24 @@
+import org.elasticsearch.gradle.OS
+import org.elasticsearch.gradle.VersionProperties
+import org.elasticsearch.gradle.info.BuildParams
+
+apply plugin: 'elasticsearch.jdk-download'
+
+jdks {
+    provisioned_runtime {
+        vendor = VersionProperties.bundledJdkVendor
+        version = VersionProperties.getBundledJdk(OS.current().name().toLowerCase())
+        platform = OS.current().name().toLowerCase()
+    }
+}
+
+allprojects {
+    project.tasks.withType(Test).configureEach { Test test ->
+        if (BuildParams.getIsRuntimeJavaHomeSet()) {
+            test.executable = "${BuildParams.runtimeJavaHome}/bin/java"
+        } else {
+            test.dependsOn(rootProject.jdks.provisioned_runtime)
+            test.executable = rootProject.jdks.provisioned_runtime.getBinJavaPath()
+        }
+    }
+}