Add recipe for LifeCycleTasks.registerPreBuild() API

Bug: n/a
Test: this is a test
Change-Id: I0db17b0fa9d1ad71907c91df925a62960283c1e6

BUILD

@@ -157,3 +157,7 @@ recipe_test(
 recipe_test(
     name = "variantOutput",
 )
+
+recipe_test(
+    name = "registerPreBuild",
+)

recipes/registerPreBuild/README.md

@@ -0,0 +1,32 @@
+# Register tasks to run before build using LifecycleTasks.registerPreBuild()
+
+This sample demonstrates how to use the [`LifecycleTasks.registerPreBuild()`](https://developer.android.com/reference/tools/gradle-api/current/com/android/build/api/variant/LifecycleTasks#registerPreBuild(kotlin.Array)) API
+to register tasks to run before a build begins.
+
+| Module                     | Content                                                     |
+|----------------------------|-------------------------------------------------------------|
+| [build-logic](build-logic) | Contains the Project plugin that is the core of the recipe. |
+| [app](app)                 | An Android application that has the plugin applied.         |
+
+The [build-logic](build-logic) sub-project contains the [`CustomPlugin`](build-logic/plugins/src/main/kotlin/CustomPlugin.kt)
+and [`PreBuildValidationTask`](build-logic/plugins/src/main/kotlin/PreBuildValidationTask.kt) classes.
+
+[`CustomPlugin`](build-logic/plugins/src/main/kotlin/CustomPlugin.kt) contains the creation of the task provider for the [`PreBuildValidationTask`](build-logic/plugins/src/main/kotlin/PreBuildValidationTask.kt). The API call
+to register this task per-variant is below:
+
+```
+androidComponents.onVariants { variant ->
+    variant.lifecycleTasks.registerPreBuild(preBuildTaskProvider)
+}
+```
+
+[`CustomPlugin`](build-logic/plugins/src/main/kotlin/CustomPlugin.kt) also registers the `ValidateTask` which verifies that the pre-build task ran.
+
+## To Run
+To run the example, you can just do
+
+```
+./gradlew :app:build
+```
+
+and you should see the file created by the task in `app/build/preBuildOutput/gradle_version.txt`.

recipes/registerPreBuild/app/build.gradle.kts

@@ -0,0 +1,36 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+plugins {
+    alias(libs.plugins.android.application)
+    alias(libs.plugins.kotlin.android)
+    id("android.recipes.register_pre_build")
+}
+
+android {
+    namespace = "com.example.android.recipes.register_pre_build"
+    compileSdk = $COMPILE_SDK
+    defaultConfig {
+       minSdk = $MINIMUM_SDK
+       targetSdk = $COMPILE_SDK
+    }
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(17))
+    }
+}

recipes/registerPreBuild/app/src/main/AndroidManifest.xml

@@ -0,0 +1,17 @@
+<?xml version="1.0" encoding="utf-8"?>
+<manifest xmlns:android="http://schemas.android.com/apk/res/android">
+    <!--
+         Copyright 2024 The Android Open Source Project
+         Licensed under the Apache License, Version 2.0 (the "License");
+         you may not use this file except in compliance with the License.
+         You may obtain a copy of the License at
+              http://www.apache.org/licenses/LICENSE-2.0
+         Unless required by applicable law or agreed to in writing, software
+         distributed under the License is distributed on an "AS IS" BASIS,
+         WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+         See the License for the specific language governing permissions and
+         limitations under the License.
+    -->
+    <application android:label="Minimal">
+    </application>
+</manifest>

recipes/registerPreBuild/build-logic/gradle.properties

@@ -0,0 +1,2 @@
+# Gradle properties are not passed to included builds https://github.com/gradle/gradle/issues/2534
+org.gradle.parallel=true

recipes/registerPreBuild/build-logic/gradle/libs.versions.toml

@@ -0,0 +1,9 @@
+[versions]
+androidGradlePlugin = $AGP_VERSION
+kotlin = $KOTLIN_VERSION
+
+[libraries]
+android-gradlePlugin-api = { group = "com.android.tools.build", name = "gradle-api", version.ref = "androidGradlePlugin" }
+
+[plugins]
+kotlin-jvm = { id = "org.jetbrains.kotlin.jvm", version.ref = "kotlin" }

recipes/registerPreBuild/build-logic/plugins/build.gradle.kts

@@ -0,0 +1,40 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+plugins {
+    `java-gradle-plugin`
+    alias(libs.plugins.kotlin.jvm)
+}
+
+java {
+    toolchain {
+        languageVersion.set(JavaLanguageVersion.of(17))
+    }
+}
+
+dependencies {
+    compileOnly(libs.android.gradlePlugin.api)
+    implementation(gradleKotlinDsl())
+}
+
+gradlePlugin {
+    plugins {
+        create("customPlugin") {
+            id = "android.recipes.register_pre_build"
+            implementationClass = "CustomPlugin"
+        }
+    }
+}

recipes/registerPreBuild/build-logic/plugins/src/main/kotlin/CustomPlugin.kt

@@ -0,0 +1,84 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ *   Licensed under the Apache License, Version 2.0 (the "License");
+ *   you may not use this file except in compliance with the License.
+ *   You may obtain a copy of the License at
+ *
+ *       https://www.apache.org/licenses/LICENSE-2.0
+ *
+ *   Unless required by applicable law or agreed to in writing, software
+ *   distributed under the License is distributed on an "AS IS" BASIS,
+ *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ *   See the License for the specific language governing permissions and
+ *   limitations under the License.
+ */
+
+import com.android.build.api.variant.AndroidComponentsExtension
+import com.android.build.gradle.AppPlugin
+import org.gradle.api.Plugin
+import org.gradle.api.DefaultTask
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.Project
+import org.gradle.api.tasks.InputDirectory
+import org.gradle.api.tasks.TaskAction
+import org.gradle.configurationcache.extensions.capitalized
+import org.gradle.kotlin.dsl.register
+
+/**
+ * This custom plugin will register a callback that is applied to all variants.
+ */
+class CustomPlugin : Plugin<Project> {
+    override fun apply(project: Project) {
+        // Registers a callback on the application of the Android Application plugin.
+        // This allows the CustomPlugin to work whether it's applied before or after
+        // the Android Application plugin.
+        project.plugins.withType(AppPlugin::class.java) {
+
+            // Create the provider for the pre-build task
+            val preBuildTaskProvider = project.tasks.register<PreBuildValidationTask>("preBuildValidation") {
+                gradleVersion.set(project.gradle.gradleVersion)
+                output.set(project.layout.buildDirectory.dir("preBuildOutput"))
+            }
+
+            val androidComponents = project.extensions.getByType(AndroidComponentsExtension::class.java)
+
+            // Registers a callback to be called, when a new variant is configured
+            androidComponents.onVariants { variant ->
+                // Register the pre-build task with the LifecycleTask API
+                variant.lifecycleTasks.registerPreBuild(preBuildTaskProvider)
+
+                // -- Verification --
+                // the following is just to validate the recipe and is not actually part of the recipe itself
+                project.tasks.register<ValidateTask>("validate${variant.name.capitalized()}") {
+                    // The input of the validation task should be the output of the pre-build task.
+                    // The normal way to do this would be:
+                    //     input.set(preBuildTaskProvider.flatMap { it.output }
+                    // However, doing this will force running the pre-build task when we want it to run
+                    // automatically when build is invoked.
+                    // So we set the input manually, and the validation task will have to be called
+                    // separately (in a separate Gradle execution or Gradle will detect the
+                    // lack of dependency between the 2 tasks and complain).
+                    input.set(project.layout.buildDirectory.dir("preBuildOutput"))
+                }
+            }
+        }
+    }
+}
+
+/**
+ * Validation task to verify the behavior of the recipe
+ */
+abstract class ValidateTask : DefaultTask() {
+
+    @get:InputDirectory
+    abstract val input: DirectoryProperty
+
+    @TaskAction
+    fun taskAction() {
+        val gradleVersionFile = input.get().file("gradle_version.txt").asFile
+        if (!gradleVersionFile.exists()) {
+            throw RuntimeException("Expected file missing: $gradleVersionFile")
+        }
+    }
+}

recipes/registerPreBuild/build-logic/plugins/src/main/kotlin/PreBuildValidationTask.kt

@@ -0,0 +1,56 @@
+/*
+ * Copyright (C) 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.gradle.api.DefaultTask
+import org.gradle.api.tasks.Input
+import org.gradle.api.tasks.TaskAction
+import org.gradle.api.tasks.OutputDirectory
+import org.gradle.api.file.DirectoryProperty
+import org.gradle.api.provider.Property
+import java.io.File
+
+/**
+ * This is the pre-build task that runs before the build executes.
+ * The task does a trivial validation of the Gradle version, and produces an output for verification in another task.
+ */
+abstract class PreBuildValidationTask : DefaultTask() {
+
+    // In order for the task to be up-to-date when the inputs have not changed,
+    // the task must declare an output, even if it's not used. Tasks with no
+    // output are always run regardless of whether the inputs changed
+    @get:OutputDirectory
+    abstract val output: DirectoryProperty
+
+    @get:Input
+    abstract val gradleVersion: Property<String>
+
+    @TaskAction
+    fun taskAction() {
+        // This is a trivial validation, but a more useful one could be used in this task
+        if (gradleVersion.get().isEmpty()) {
+            throw RuntimeException("The Gradle version must not be empty.")
+        }
+
+        // The next part of this task is done only for verification purposes
+        // delete the previous content. This task does not support incremental mode but could be modified to do so
+        val outputFile = output.get().asFile
+        outputFile.deleteRecursively()
+        outputFile.mkdirs()
+
+        val newFile = File(outputFile, "gradle_version.txt")
+        newFile.writeText(gradleVersion.get())
+    }
+}

recipes/registerPreBuild/build-logic/settings.gradle.kts

@@ -0,0 +1,33 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+rootProject.name = "build-logic"
+
+pluginManagement {
+    repositories {
+        $AGP_REPOSITORY
+        $PLUGIN_REPOSITORIES
+    }
+}
+
+dependencyResolutionManagement {
+    repositories {
+        $AGP_REPOSITORY
+        $DEPENDENCY_REPOSITORIES
+    }
+}
+
+include(":plugins")

recipes/registerPreBuild/build.gradle.kts

@@ -0,0 +1,20 @@
+/*
+ * Copyright 2024 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     https://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+plugins {
+    alias(libs.plugins.android.application) apply false
+    alias(libs.plugins.kotlin.android) apply false
+}

recipes/registerPreBuild/gradle.properties

@@ -0,0 +1,23 @@
+# Project-wide Gradle settings.
+# IDE (e.g. Android Studio) users:
+# Gradle settings configured through the IDE *will override*
+# any settings specified in this file.
+# For more details on how to configure your build environment visit
+# http://www.gradle.org/docs/current/userguide/build_environment.html
+# Specifies the JVM arguments used for the daemon process.
+# The setting is particularly useful for tweaking memory settings.
+org.gradle.jvmargs=-Xmx2048m -Dfile.encoding=UTF-8
+# When configured, Gradle will run in incubating parallel mode.
+# This option should only be used with decoupled projects. More details, visit
+# http://www.gradle.org/docs/current/userguide/multi_project_builds.html#sec:decoupled_projects
+org.gradle.parallel=true
+# AndroidX package structure to make it clearer which packages are bundled with the
+# Android operating system, and which are packaged with your app's APK
+# https://developer.android.com/topic/libraries/support-library/androidx-rn
+android.useAndroidX=true
+# Kotlin code style for this project: "official" or "obsolete":
+kotlin.code.style=official
+# Enables namespacing of each library's R class so that its R class includes only the
+# resources declared in the library itself and none from the library's dependencies,
+# thereby reducing the size of the R class for that library
+android.nonTransitiveRClass=true

recipes/registerPreBuild/gradle/libs.versions.toml

@@ -0,0 +1,9 @@
+[versions]
+androidGradlePlugin = $AGP_VERSION
+kotlin = $KOTLIN_VERSION
+
+[plugins]
+android-application = { id = "com.android.application", version.ref = "androidGradlePlugin" }
+kotlin-android = { id = "org.jetbrains.kotlin.android", version.ref = "kotlin" }
+
+