Add code to ensure locales declaration consistency

By comparing the locales limited by the `resourcesConfiguration` field in a product flavor with the ones we hardcoded in our Fastlane scripts.

This way if we decide to update either place in the future (e.g. add new locales to download from GlotPress for Jetpack by updating the `JP_APP_LOCALES` constant in `fastlane/lanes/localization.rb`) we'll be reminded to ensure we updated the other as well (i.e. the `resourceConfigurations` in the `jetpack` flavor of the `WordPress/build.gradle` file)

Author: AliSoftware

WordPress/build.gradle

@@ -603,6 +603,16 @@ tasks.register("printAllVersions") {
     }
 }
 
+tasks.register("printResourceConfigurations") {
+    doLast {
+        android.productFlavors.each { flavor ->
+            if (flavor.dimension == "app") {
+                println "${flavor.name}: ${flavor.resourceConfigurations}"
+            }
+        }
+    }
+}
+
 def checkGradlePropertiesFile() {
     def inputFile = file("${rootDir}/gradle.properties")
     if (!inputFile.exists()) {

fastlane/lanes/localization.rb

@@ -390,17 +390,17 @@
   #####################################################################################
   lane :download_translations do
     # WordPress strings
-    wordpress_res_dir = File.join('WordPress', 'src', 'main', 'res')
+    check_declared_locales_consistency(app_flavor: 'wordpress', locales_list: WP_APP_LOCALES)
     android_download_translations(
-      res_dir: wordpress_res_dir,
+      res_dir: File.join('WordPress', 'src', 'main', 'res'),
       glotpress_url: APP_SPECIFIC_VALUES[:wordpress][:glotpress_appstrings_project],
       locales: WP_APP_LOCALES
     )
 
     # Jetpack strings
-    jetpack_res_dir = File.join('WordPress', 'src', 'jetpack', 'res')
+    check_declared_locales_consistency(app_flavor: 'jetpack', locales_list: JP_APP_LOCALES)
     android_download_translations(
-      res_dir: jetpack_res_dir,
+      res_dir: File.join('WordPress', 'src', 'jetpack', 'res'),
       glotpress_url: APP_SPECIFIC_VALUES[:jetpack][:glotpress_appstrings_project],
       locales: JP_APP_LOCALES
     )
@@ -421,4 +421,32 @@ def update_po_file_for_metadata_localization(po_path:, sources:, release_version
     git_add(path: po_path)
     git_commit(path: po_path, message: commit_message, allow_nothing_to_commit: true)
   end
+
+  # Compares the list of locales declared in the `resourceConfigurations` field of `build.gradle` for a given flavor
+  # with the hardcoded list of locales we use in our Fastlane lanes, to ensure they match and we are consistent.
+  #
+  # @param [String] app_flavor `"wordpress"` or `"jetpack"` — The `productFlavor` to read from in the build.gradle
+  # @param [Array<Hash>] locales_list The list of Hash defining the locales to compare that list to.
+  #        Typically one of the `WP_APP_LOCALES` or `JP_APP_LOCALES` constants
+  def check_declared_locales_consistency(app_flavor:, locales_list:)
+    output = gradle(task: 'printResourceConfigurations')
+    resource_configs = output.match(/^#{app_flavor}: \[(.*)\]$/)&.captures&.first&.gsub(' ','')&.split(',')&.sort
+    if resource_configs.nil? || resource_configs.empty?
+      UI.message("No `resourceConfigurations` field set in `build.gradle` for the `#{app_flavor}` flavor. Nothing to check.")
+      return
+    end
+
+    expected_locales = locales_list.map { |l| l[:android] }.sort
+    if resource_configs == expected_locales
+      UI.message("The `resourceConfigurations` field set in `build.gradle` for the `#{app_flavor}` flavor matches what is set in our Fastfile. All is good!")
+    else
+      UI.user_error! <<~ERROR
+        The list of `resourceConfigurations` declared in your `build.gradle` for the `#{app_flavor}` flavor
+        does not match the list of locales we hardcoded in the `fastlane/lanes/localization.rb` for this app.
+
+        If you recently updated the hardcoded list of locales to include for this app, be sure to apply those
+        changes in both places, to keep the Fastlane scripts consistent with the gradle configuration of your app.
+      ERROR
+    end
+  end
 end