Improve i18n Integration

* Better error message if the value of the i18n directory is invalid.
* Added test for configuration error message.
* DRY'd up code for checking if this config value is set.
* Improved comments in sample react_on_rails.rb config file

lib/generators/react_on_rails/templates/base/base/config/initializers/react_on_rails.rb.tt

@@ -62,7 +62,8 @@ ReactOnRails.configure do |config|
   ################################################################################
   # I18N OPTIONS
   ################################################################################
-  # Replace the following line to the location where you keep translation.js & default.js.
+  # Replace the following line to the location where you keep translation.js & default.js for use
+  # by the npm packages react-intl. Be sure this directory exists!
   # config.i18n_dir = Rails.root.join("client", "app", "libs", "i18n")
 
   ################################################################################

lib/react_on_rails/configuration.rb

@@ -11,6 +11,16 @@ def self.setup_config_values
     configure_generated_assets_dirs_deprecation
     ensure_generated_assets_dir_present
     ensure_server_bundle_js_file_has_no_path
+    check_i18n_directory_exists
+  end
+
+  def self.check_i18n_directory_exists
+    return unless @configuration.i18n_dir.present?
+    return if Dir.exist?(@configuration.i18n_dir)
+
+    raise "Error configuring /config/react_on_rails.rb: invalid value for `config.i18n_dir`. "\
+        "Directory does not exist: #{@configuration.i18n_dir}. Set to value to nil or comment it "\
+        "out if not using this i18n with React on Rails."
   end
 
   def self.ensure_generated_assets_dir_present

lib/react_on_rails/locales_to_js.rb

@@ -3,6 +3,7 @@
 module ReactOnRails
   class LocalesToJs
     def initialize
+      return unless i18n_dir.present?
       return unless obsolete?
       @translations, @defaults = generate_translations
       convert
@@ -38,7 +39,8 @@ def js_file(name)
     end
 
     def locale_files
-      @locale_files ||= Rails.application.config.i18n.load_path
+      @locale_files ||=
+        (Rails.application && Rails.application.config.i18n.load_path).presence
     end
 
     def i18n_dir

lib/react_on_rails/test_helper/ensure_assets_compiled.rb

@@ -27,9 +27,7 @@ def call
         # Be sure we don't do this again.
         self.class.has_been_run = true
 
-        if ReactOnRails.configuration.i18n_dir.present? && Rails.application.present?
-          ReactOnRails::LocalesToJs.new
-        end
+        ReactOnRails::LocalesToJs.new
 
         stale_gen_files = webpack_assets_status_checker.stale_generated_webpack_files
 

lib/tasks/locale.rake

@@ -7,8 +7,6 @@ This task generates javascript locale files: `translations.js` & `default.js` an
 the "ReactOnRails.configuration.i18n_dir".
   DESC
   task locale: :environment do
-    if ReactOnRails.configuration.i18n_dir.present?
-      ReactOnRails::LocalesToJs.new
-    end
+    ReactOnRails::LocalesToJs.new
   end
 end

spec/dummy/config/initializers/react_on_rails.rb

@@ -74,7 +74,8 @@ def self.custom_context(view_context)
   ################################################################################
   # I18N OPTIONS
   ################################################################################
-  # Replace the following line to the location where you keep translation.js & default.js.
+  # Replace the following line to the location where you keep translation.js & default.js for use
+  # by the npm packages react-intl. Be sure this directory exists!
   # config.i18n_dir = Rails.root.join("client", "app", "libs", "i18n")
 
   ################################################################################

spec/react_on_rails/configuration_spec.rb

@@ -2,6 +2,25 @@
 
 module ReactOnRails
   RSpec.describe Configuration do
+    it "raises if the i18n directory does not exist" do
+      junk_name = "/XXXX/junkXXXX"
+      expect do
+        ReactOnRails.configure do |config|
+          config.i18n_dir = junk_name
+        end
+      end.to raise_error(/#{junk_name}/)
+    end
+
+    it "does not raises if the i18n directory does exist" do
+      dir = File.expand_path(File.dirname(__FILE__))
+      expect do
+        ReactOnRails.configure do |config|
+          config.i18n_dir = dir
+        end
+      end.to_not raise_error
+      expect(ReactOnRails.configuration.i18n_dir).to eq(dir)
+    end
+
     it "be able to config default configuration of the gem" do
       ReactOnRails.configure do |config|
         config.server_bundle_js_file = "server.js"

spec/react_on_rails/locales_to_js_spec.rb

@@ -16,6 +16,12 @@ module ReactOnRails
       end
     end
 
+    after do
+      ReactOnRails.configure do |config|
+        config.i18n_dir = nil
+      end
+    end
+
     context "with obsolete js files" do
       before do
         FileUtils.touch(translations_path, mtime: Time.now - 1.year)