Let RNGP set buildConfigFields for New Architecture and Hermes

Summary:
This diff further simplifies the New App Template by removing the
buildConfigFields for both Hermes and New Architecture with the React Native Gradle Plugin.

Changelog:
[Android] [Changed] - Let RNGP set buildConfigFields for New Architecture and Hermes

Reviewed By: cipolleschi

Differential Revision: D40139559

fbshipit-source-id: 202b6ac9c4c036a026a2ff3e8279087ffd363eaa

packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/ReactPlugin.kt

@@ -15,6 +15,7 @@ import com.android.build.gradle.internal.tasks.factory.dependsOn
 import com.facebook.react.tasks.BuildCodegenCLITask
 import com.facebook.react.tasks.GenerateCodegenArtifactsTask
 import com.facebook.react.tasks.GenerateCodegenSchemaTask
+import com.facebook.react.utils.AgpConfiguratorUtils.configureBuildConfigFields
 import com.facebook.react.utils.JsonUtils
 import com.facebook.react.utils.NdkConfiguratorUtils.configureReactNativeNdk
 import com.facebook.react.utils.findPackageJsonFile
@@ -55,6 +56,7 @@ class ReactPlugin : Plugin<Project> {
 
   private fun applyAppPlugin(project: Project, config: ReactExtension) {
     configureReactNativeNdk(project, config)
+    configureBuildConfigFields(project)
     project.afterEvaluate {
       if (config.applyAppPlugin.getOrElse(false)) {
         val androidConfiguration = project.extensions.getByType(BaseExtension::class.java)

packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/AgpConfiguratorUtils.kt

@@ -0,0 +1,32 @@
+/*
+ * Copyright (c) Meta Platforms, Inc. and affiliates.
+ *
+ * This source code is licensed under the MIT license found in the
+ * LICENSE file in the root directory of this source tree.
+ */
+
+package com.facebook.react.utils
+
+import com.android.build.api.variant.AndroidComponentsExtension
+import com.facebook.react.utils.ProjectUtils.isHermesEnabled
+import com.facebook.react.utils.ProjectUtils.isNewArchEnabled
+import org.gradle.api.Action
+import org.gradle.api.Project
+import org.gradle.api.plugins.AppliedPlugin
+
+internal object AgpConfiguratorUtils {
+  @Suppress("UnstableApiUsage")
+  fun configureBuildConfigFields(project: Project) {
+    val action =
+        Action<AppliedPlugin> {
+          project.extensions.getByType(AndroidComponentsExtension::class.java).finalizeDsl { ext ->
+            ext.defaultConfig.buildConfigField(
+                "boolean", "IS_NEW_ARCHITECTURE_ENABLED", project.isNewArchEnabled.toString())
+            ext.defaultConfig.buildConfigField(
+                "boolean", "IS_HERMES_ENABLED", project.isHermesEnabled.toString())
+          }
+        }
+    project.pluginManager.withPlugin("com.android.application", action)
+    project.pluginManager.withPlugin("com.android.library", action)
+  }
+}

packages/react-native-gradle-plugin/src/main/kotlin/com/facebook/react/utils/ProjectUtils.kt

@@ -14,4 +14,22 @@ internal object ProjectUtils {
     get() =
         project.hasProperty("newArchEnabled") &&
             project.property("newArchEnabled").toString().toBoolean()
+
+  const val HERMES_FALLBACK = true
+
+  internal val Project.isHermesEnabled: Boolean
+    get() =
+        if (project.hasProperty("enableHermes")) {
+          project.property("enableHermes").toString().lowercase().toBooleanStrictOrNull() ?: true
+        } else if (project.extensions.extraProperties.has("react")) {
+          @Suppress("UNCHECKED_CAST")
+          val reactMap = project.extensions.extraProperties.get("react") as? Map<String, Any?>
+          when (val enableHermesKey = reactMap?.get("enableHermes")) {
+            is Boolean -> enableHermesKey
+            is String -> enableHermesKey.lowercase().toBooleanStrictOrNull() ?: true
+            else -> HERMES_FALLBACK
+          }
+        } else {
+          HERMES_FALLBACK
+        }
 }

packages/react-native-gradle-plugin/src/test/kotlin/com/facebook/react/utils/ProjectUtilsTest.kt

@@ -8,6 +8,7 @@
 package com.facebook.react.utils
 
 import com.facebook.react.tests.createProject
+import com.facebook.react.utils.ProjectUtils.isHermesEnabled
 import com.facebook.react.utils.ProjectUtils.isNewArchEnabled
 import org.junit.Assert.assertFalse
 import org.junit.Assert.assertTrue
@@ -40,4 +41,62 @@ class ProjectUtilsTest {
     project.extensions.extraProperties.set("newArchEnabled", "¯\\_(ツ)_/¯")
     assertFalse(project.isNewArchEnabled)
   }
+
+  @Test
+  fun isHermesEnabled_returnsTrueByDefault() {
+    assertTrue(createProject().isHermesEnabled)
+  }
+
+  @Test
+  fun isNewArchEnabled_withDisabledViaProperty_returnsFalse() {
+    val project = createProject()
+    project.extensions.extraProperties.set("enableHermes", "false")
+    assertFalse(project.isHermesEnabled)
+  }
+
+  @Test
+  fun isHermesEnabled_withEnabledViaProperty_returnsTrue() {
+    val project = createProject()
+    project.extensions.extraProperties.set("enableHermes", "true")
+    assertTrue(project.isHermesEnabled)
+  }
+
+  @Test
+  fun isHermesEnabled_withInvalidViaProperty_returnsTrue() {
+    val project = createProject()
+    project.extensions.extraProperties.set("enableHermes", "¯\\_(ツ)_/¯")
+    assertTrue(project.isHermesEnabled)
+  }
+
+  @Test
+  fun isHermesEnabled_withDisabledViaExt_returnsFalse() {
+    val project = createProject()
+    val extMap = mapOf("enableHermes" to false)
+    project.extensions.extraProperties.set("react", extMap)
+    assertFalse(project.isHermesEnabled)
+  }
+
+  @Test
+  fun isHermesEnabled_withEnabledViaExt_returnsTrue() {
+    val project = createProject()
+    val extMap = mapOf("enableHermes" to true)
+    project.extensions.extraProperties.set("react", extMap)
+    assertTrue(project.isHermesEnabled)
+  }
+
+  @Test
+  fun isHermesEnabled_withDisabledViaExtAsString_returnsFalse() {
+    val project = createProject()
+    val extMap = mapOf("enableHermes" to "false")
+    project.extensions.extraProperties.set("react", extMap)
+    assertFalse(project.isHermesEnabled)
+  }
+
+  @Test
+  fun isHermesEnabled_withInvalidViaExt_returnsTrue() {
+    val project = createProject()
+    val extMap = mapOf("enableHermes" to "¯\\_(ツ)_/¯")
+    project.extensions.extraProperties.set("react", extMap)
+    assertTrue(project.isHermesEnabled)
+  }
 }