Reload I18n locales in development

activesupport/lib/active_support/i18n_railtie.rb

@@ -37,10 +37,12 @@ module I18n
       enforce_available_locales = I18n.enforce_available_locales if enforce_available_locales.nil?
       I18n.enforce_available_locales = false
 
+      reloadable_paths = []
       app.config.i18n.each do |setting, value|
         case setting
         when :railties_load_path
-          app.config.i18n.load_path.unshift(*value)
+          reloadable_paths = value
+          app.config.i18n.load_path.unshift(*value.map(&:existent).flatten)
         when :load_path
           I18n.load_path += value
         else
@@ -53,7 +55,14 @@ module I18n
       # Restore available locales check so it will take place from now on.
       I18n.enforce_available_locales = enforce_available_locales
 
-      reloader = ActiveSupport::FileUpdateChecker.new(I18n.load_path.dup){ I18n.reload! }
+      directories = watched_dirs_with_extensions(reloadable_paths)
+      reloader = ActiveSupport::FileUpdateChecker.new(I18n.load_path.dup, directories) do
+        I18n.load_path.keep_if { |p| File.exist?(p) }
+        I18n.load_path |= reloadable_paths.map(&:existent).flatten
+
+        I18n.reload!
+      end
+
       app.reloaders << reloader
       ActionDispatch::Reloader.to_prepare do
         reloader.execute_if_updated
@@ -96,5 +105,11 @@ module I18n
         raise "Unexpected fallback type #{fallbacks.inspect}"
       end
     end
+
+    def self.watched_dirs_with_extensions(paths)
+      paths.each_with_object({}) do |path, result|
+        result[path.absolute_current] = path.extensions
+      end
+    end
   end
 end

railties/lib/rails/engine.rb

@@ -589,7 +589,7 @@ module Rails
     # I18n load paths are a special case since the ones added
     # later have higher priority.
     initializer :add_locales do
-      config.i18n.railties_load_path.concat(paths["config/locales"].existent)
+      config.i18n.railties_load_path << paths["config/locales"]
     end
 
     initializer :add_view_paths do

railties/lib/rails/paths.rb

@@ -123,6 +123,11 @@ module Rails
         options[:load_path]     ? load_path!     : skip_load_path!
       end
 
+      # :nodoc:
+      def absolute_current
+        File.expand_path(@current, @root.path)
+      end
+
       def children
         keys = @root.keys.find_all { |k|
           k.start_with?(@current) && k != @current
@@ -175,6 +180,11 @@ module Rails
         @paths
       end
 
+      # :nodoc:
+      def extensions
+        $1.split(',') if @glob =~ /\{([\S]+)\}/
+      end
+
       # Expands all paths against the root and return all unique values.
       def expanded
         raise "You need to set a path root" unless @root.path

railties/test/application/initializers/i18n_test.rb

@@ -132,6 +132,79 @@ en:
       assert_equal "2", last_response.body
     end
 
+    test "new locale files are loaded" do
+      add_to_config <<-RUBY
+        config.cache_classes = false
+      RUBY
+
+      app_file "config/locales/en.yml", <<-YAML
+en:
+  foo: "1"
+      YAML
+
+      app_file 'config/routes.rb', <<-RUBY
+        Rails.application.routes.draw do
+          get '/i18n',   :to => lambda { |env| [200, {}, [I18n.t(:foo)]] }
+        end
+      RUBY
+
+      require 'rack/test'
+      extend Rack::Test::Methods
+      load_app
+
+      get "/i18n"
+      assert_equal "1", last_response.body
+
+      # Wait a full second so we have time for changes to propagate
+      sleep(1)
+
+      remove_file "config/locales/en.yml"
+      app_file "config/locales/custom.en.yml", <<-YAML
+en:
+  foo: "2"
+      YAML
+
+      get "/i18n"
+      assert_equal "2", last_response.body
+    end
+
+    test "I18n.load_path is reloaded" do
+      add_to_config <<-RUBY
+        config.cache_classes = false
+      RUBY
+
+      app_file "config/locales/en.yml", <<-YAML
+en:
+  foo: "1"
+      YAML
+
+      app_file 'config/routes.rb', <<-RUBY
+        Rails.application.routes.draw do
+          get '/i18n',   :to => lambda { |env| [200, {}, [I18n.load_path.inspect]] }
+        end
+      RUBY
+
+      require 'rack/test'
+      extend Rack::Test::Methods
+      load_app
+
+      get "/i18n"
+
+      assert_match "en.yml", last_response.body
+
+      # Wait a full second so we have time for changes to propagate
+      sleep(1)
+
+      app_file "config/locales/fr.yml", <<-YAML
+fr:
+  foo: "2"
+      YAML
+
+      get "/i18n"
+      assert_match "fr.yml", last_response.body
+      assert_match "en.yml", last_response.body
+    end
+
     # Fallbacks
     test "not using config.i18n.fallbacks does not initialize I18n.fallbacks" do
       I18n.backend = Class.new(I18n::Backend::Simple).new

railties/test/paths_test.rb

@@ -62,6 +62,13 @@ class PathsTest < ActiveSupport::TestCase
     assert_equal ["/foo/bar/baz"], @root["app/models"].to_a
   end
 
+  test "absolute current path" do
+    @root.add "config"
+    @root.add "config/locales"
+
+    assert_equal "/foo/bar/config/locales", @root["config/locales"].absolute_current
+  end
+
   test "adding multiple physical paths as an array" do
     @root.add "app", with: ["/app", "/app2"]
     assert_equal ["/app", "/app2"], @root["app"].to_a
@@ -215,6 +222,12 @@ class PathsTest < ActiveSupport::TestCase
     assert_equal "*.rb", @root["app"].glob
   end
 
+  test "it should be possible to get extensions by glob" do
+    @root["app"] = "/app"
+    @root["app"].glob = "*.{rb,yml}"
+    assert_equal ["rb", "yml"], @root["app"].extensions
+  end
+
   test "it should be possible to override a path's default glob without assignment" do
     @root.add "app", with: "/app", glob: "*.rb"
     assert_equal "*.rb", @root["app"].glob