Allow configuration cache compatibility

modules/openapi-generator-gradle-plugin/src/main/kotlin/org/openapitools/generator/gradle/plugin/tasks/GenerateTask.kt

@@ -16,8 +16,12 @@
 
 package org.openapitools.generator.gradle.plugin.tasks
 
+import javax.inject.Inject
 import org.gradle.api.DefaultTask
 import org.gradle.api.GradleException
+import org.gradle.api.Project
+import org.gradle.api.file.FileSystemOperations
+import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import org.gradle.api.tasks.CacheableTask
 import org.gradle.api.tasks.Input
@@ -35,6 +39,7 @@ import org.gradle.internal.logging.text.StyledTextOutputFactory
 import org.gradle.kotlin.dsl.listProperty
 import org.gradle.kotlin.dsl.mapProperty
 import org.gradle.kotlin.dsl.property
+import org.gradle.util.GradleVersion
 import org.openapitools.codegen.CodegenConstants
 import org.openapitools.codegen.DefaultGenerator
 import org.openapitools.codegen.config.CodegenConfigurator
@@ -52,7 +57,8 @@ import org.openapitools.codegen.config.MergedSpecBuilder
  */
 @Suppress("UnstableApiUsage")
 @CacheableTask
-open class GenerateTask : DefaultTask() {
+open class GenerateTask @Inject constructor(private val objectFactory: ObjectFactory) : DefaultTask() {
+
     /**
      * The verbosity of generation
      */
@@ -540,6 +546,14 @@ open class GenerateTask : DefaultTask() {
 
     protected open fun createDefaultCodegenConfigurator(): CodegenConfigurator = CodegenConfigurator()
 
+    private fun createFileSystemManager(): FileSystemManager {
+        return if(GradleVersion.current() >= GradleVersion.version("6.0")) {
+            objectFactory.newInstance(FileSystemManagerDefault::class.java)
+        } else {
+            objectFactory.newInstance(FileSystemManagerLegacy::class.java, project)
+        }
+    }
+
     @Suppress("unused")
     @TaskAction
     fun doWork() {
@@ -550,7 +564,7 @@ open class GenerateTask : DefaultTask() {
 
         cleanupOutput.ifNotEmpty { cleanup ->
             if (cleanup) {
-                project.delete(outputDir)
+                createFileSystemManager().delete(outputDir)
                 val out = services.get(StyledTextOutputFactory::class.java).create("openapi")
                 out.withStyle(StyledTextOutput.Style.Success)
                 out.println("Cleaned up output directory ${outputDir.get()} before code generation (cleanupOutput set to true).")
@@ -849,3 +863,23 @@ open class GenerateTask : DefaultTask() {
         }
     }
 }
+
+internal interface FileSystemManager {
+
+    fun delete(outputDir: Property<String>)
+
+}
+
+internal open class FileSystemManagerLegacy @Inject constructor(private val project: Project): FileSystemManager {
+
+    override fun delete(outputDir: Property<String>) {
+        project.delete(outputDir)
+    }
+}
+
+internal open class FileSystemManagerDefault @Inject constructor(private val fs: FileSystemOperations) : FileSystemManager {
+
+    override fun delete(outputDir: Property<String>) {
+        fs.delete { delete(outputDir) }
+    }
+}

modules/openapi-generator-gradle-plugin/src/test/kotlin/GenerateTaskConfigurationCacheTest.kt

@@ -0,0 +1,129 @@
+package org.openapitools.generator.gradle.plugin
+
+import org.gradle.testkit.runner.TaskOutcome
+import org.testng.SkipException
+import org.testng.annotations.BeforeMethod
+import org.testng.annotations.DataProvider
+import org.testng.annotations.Test
+import java.io.File
+import kotlin.test.assertEquals
+import kotlin.test.assertTrue
+
+class GenerateTaskConfigurationCacheTest : TestBase() {
+
+    private lateinit var projectDirCC: File
+
+    @BeforeMethod
+    override fun before() {
+        initialize()
+        projectDirCC = temp.resolve("projectDirCC").apply { mkdir() }
+    }
+
+    @DataProvider(name = "gradle_version_provider")
+    private fun gradleVersionProviderWithConfigurationCache(): Array<Array<String>> = arrayOf(arrayOf("8.1.1"), arrayOf("7.6"))
+
+    @DataProvider(name = "gradle_version_provider_without_cc")
+    private fun gradleVersionProviderWithoutConfigurationCache(): Array<Array<String>> = arrayOf(arrayOf("5.6.1"))
+
+    // inputSpec tests
+
+    private val inputSpecExtensionContents = """
+        generatorName = "kotlin"
+        inputSpec = file("spec.yaml").absolutePath
+        cleanupOutput.set(true)
+        """.trimIndent()
+
+    @Test(dataProvider = "gradle_version_provider")
+    fun `openApiGenerate should reuse configuration cache`(gradleVersion: String) {
+        // Arrange
+        withProject(inputSpecExtensionContents)
+
+        // Act
+        val result1 = build {
+            withProjectDir(projectDirCC)
+            withArguments("--configuration-cache", "clean", "openApiGenerate")
+            withGradleVersion(gradleVersion)
+        }
+
+        val expectedRelativeFilePathSet = projectDirCC.toRelativeFilePathSet()
+
+        val result2 = build {
+            withProjectDir(projectDirCC)
+            withArguments("--configuration-cache", "clean", "openApiGenerate")
+            withGradleVersion(gradleVersion)
+        }
+
+        // Assert
+        assertEquals(TaskOutcome.SUCCESS, result1.task(":openApiGenerate")?.outcome)
+        assertTrue(result1.output.contains("Configuration cache entry stored."))
+        assertEquals(TaskOutcome.SUCCESS, result2.task(":openApiGenerate")?.outcome)
+        assertTrue(result2.output.contains("Configuration cache entry reused."))
+        assertEquals(expectedRelativeFilePathSet, projectDirCC.toRelativeFilePathSet())
+    }
+
+    private fun getJavaVersion(): Int {
+        val version = System.getProperty("java.version")
+        val parts = version.split('.')
+        if (parts.first() == "1") return parts.getOrElse(1) { "0" }.toInt()
+        return parts.first().toInt()
+    }
+
+    @Test(dataProvider = "gradle_version_provider_without_cc")
+    fun `openApiGenerate should work with Gradle legacy versions`(gradleVersion: String) {
+        if(getJavaVersion() > 12) {
+            // https://docs.gradle.org/current/userguide/compatibility.html
+            throw SkipException("Skipping test as Gradle ${gradleVersion} is not compatible with Java ${getJavaVersion()}")
+        }
+        // Arrange
+        withProject(inputSpecExtensionContents)
+
+        // Act
+        val result1 = build {
+            withProjectDir(projectDirCC)
+            withArguments("clean", "openApiGenerate")
+            withGradleVersion(gradleVersion)
+        }
+
+        val expectedRelativeFilePathSet = projectDirCC.toRelativeFilePathSet()
+
+        val result2 = build {
+            withProjectDir(projectDirCC)
+            withArguments("clean", "openApiGenerate")
+            withGradleVersion(gradleVersion)
+        }
+
+        // Assert
+        assertEquals(TaskOutcome.SUCCESS, result1.task(":openApiGenerate")?.outcome)
+        assertEquals(TaskOutcome.SUCCESS, result2.task(":openApiGenerate")?.outcome)
+        assertEquals(expectedRelativeFilePathSet, projectDirCC.toRelativeFilePathSet())
+    }
+
+    // Helper methods & test fixtures
+
+    private fun File.toRelativeFilePathSet() =
+        resolve("build").walk().map { it.toRelativeString(resolve("build")) }.toSet()
+
+    private fun withProject(extensionContents: String) {
+        val settingsContents = """
+            rootProject.name = "openapi-generator"
+            """.trimIndent()
+        val buildContents = """
+            plugins {
+              id 'base'
+              id 'org.openapi.generator'
+            }
+            openApiGenerate {
+                $extensionContents
+            }
+            """.trimIndent()
+        val projectFiles = mapOf(
+            "spec.yaml" to javaClass.classLoader.getResourceAsStream("specs/petstore-v3.0.yaml")!!
+        )
+        withProject(
+            projectDir = projectDirCC,
+            settingsContents = settingsContents,
+            buildContents = buildContents,
+            projectFiles = projectFiles
+        )
+    }
+}