Migrate version.gradle script plugin to Kotlin convention plugin (#11345)

build: Refactor `version.gradle` to `dd-trace-java.version-file` plugin

* `Project.exec {}` is removed in Gradle 9. It is also incompatible with
  the configuration cache.
* `gradle/version.gradle` is a Groovy script plugin, migrating to
  a convention plugin is the way to go.

build: Add new plugin tests

build: Refactor the tests with a better fixture for version plugins

Merge branch 'master' into bdu/gradle9-write-version-convention-plugin

fix: task need to be experessed as task path, in the build result

Co-authored-by: brice.dutheil <brice.dutheil@datadoghq.com>

Author: bric3

buildSrc/build.gradle.kts

@@ -39,6 +39,11 @@ gradlePlugin {
       implementationClass = "datadog.gradle.plugin.version.TracerVersionPlugin"
     }
 
+    create("version-file-plugin") {
+      id = "dd-trace-java.version-file"
+      implementationClass = "datadog.gradle.plugin.version.WriteVersionFilePlugin"
+    }
+
     create("dump-hanged-test-plugin") {
       id = "dd-trace-java.dump-hanged-test"
       implementationClass = "datadog.gradle.plugin.dump.DumpHangedTestPlugin"

buildSrc/src/main/kotlin/datadog/gradle/plugin/version/TracerVersionPlugin.kt

@@ -32,9 +32,9 @@ class TracerVersionPlugin @Inject constructor(
       providerFactory.gradleProperty("tracerVersion.qualifier")
     )
 
-    val versionProvider = versionProvider(targetProject, extension)
+    val theVersion = versionProvider(targetProject, extension)
     targetProject.allprojects {
-      version = versionProvider
+      version = theVersion
     }
   }
 

buildSrc/src/main/kotlin/datadog/gradle/plugin/version/WriteVersionFile.kt

@@ -0,0 +1,46 @@
+package datadog.gradle.plugin.version
+
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.file.ProjectLayout
+import org.gradle.api.model.ObjectFactory
+import org.gradle.api.provider.Property
+import org.gradle.api.provider.ProviderFactory
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.tasks.TaskAction
+import org.gradle.kotlin.dsl.property
+import javax.inject.Inject
+
+abstract class WriteVersionFile @Inject constructor(
+  providerFactory: ProviderFactory,
+  layout: ProjectLayout,
+  objects: ObjectFactory,
+) : DefaultTask() {
+
+  @get:Input
+  val version: Property<String> = objects.property<String>()
+    .convention(providerFactory.provider { project.version.toString() })
+
+  @get:Input
+  val gitHash: Property<String> = objects.property<String>()
+    .convention(
+      providerFactory.of(GitCommandValueSource::class.java) {
+        parameters {
+          gitCommand.addAll("git", "rev-parse", "--short", "HEAD")
+          workingDirectory.set(layout.projectDirectory)
+        }
+      }
+    )
+
+  @get:OutputDirectory
+  val outputDirectory: DirectoryProperty = objects.directoryProperty()
+    .convention(layout.buildDirectory.dir("generated/version"))
+
+  @TaskAction
+  fun writeVersionFile() {
+    val versionFile = outputDirectory.file("${project.name}.version").get().asFile
+    versionFile.parentFile.mkdirs()
+    versionFile.writeText("${version.get()}~${gitHash.get()}")
+  }
+}

buildSrc/src/main/kotlin/datadog/gradle/plugin/version/WriteVersionFilePlugin.kt

@@ -0,0 +1,19 @@
+package datadog.gradle.plugin.version
+
+import org.gradle.api.Plugin
+import org.gradle.api.Project
+import org.gradle.api.plugins.JavaPluginExtension
+import org.gradle.kotlin.dsl.register
+import org.gradle.kotlin.dsl.the
+
+class WriteVersionFilePlugin : Plugin<Project> {
+  override fun apply(target: Project) {
+    target.pluginManager.apply("java")
+
+    val writeVersionFile = target.tasks.register<WriteVersionFile>("writeVersionNumberFile")
+
+    target.the<JavaPluginExtension>().sourceSets.named("main") {
+      resources.srcDir(writeVersionFile)
+    }
+  }
+}

buildSrc/src/test/kotlin/datadog/gradle/plugin/GradleFixture.kt

@@ -151,8 +151,10 @@ internal open class GradleFixture(protected val projectDir: File) {
   /**
    * Creates or gets a file in the project directory, ensuring parent directories exist.
    */
-  protected fun file(path: String): File =
+  protected fun file(path: String, mkdirs: Boolean = true): File =
     File(projectDir, path).also { file ->
-      file.parentFile?.mkdirs()
+      if (mkdirs) {
+        file.parentFile?.mkdirs()
+      }
     }
 }