Symbolize and freeze keys when loading from YAML

lib/i18n/backend/base.rb

@@ -236,14 +236,23 @@ def load_rb(filename)
           eval(IO.read(filename), binding, filename)
         end
 
+        # Feature tests YAML load options and only selects those that
+        # are supported in the current version of Psych.
+        YAML_LOAD_OPTIONS = { symbolize_names: true, freeze: true }.select do |k, v|
+          YAML.load_file('test/test_data/locales/en.yml', **{ k => v })
+          true
+        rescue ::ArgumentError
+          false
+        end
+
         # Loads a YAML translations file. The data must have locales as
         # toplevel keys.
         def load_yml(filename)
           begin
             if YAML.respond_to?(:unsafe_load_file) # Psych 4.0 way
-              YAML.unsafe_load_file(filename)
+              YAML.unsafe_load_file(filename, **YAML_LOAD_OPTIONS)
             else
-              YAML.load_file(filename)
+              YAML.load_file(filename, **YAML_LOAD_OPTIONS)
             end
           rescue TypeError, ScriptError, StandardError => e
             raise InvalidLocaleData.new(filename, e.inspect)

test/backend/simple_test.rb

@@ -72,7 +72,12 @@ def setup
 
   test "simple load_yml: loads data from a YAML file" do
     data = I18n.backend.send(:load_yml, "#{locales_dir}/en.yml")
-    assert_equal({ 'en' => { 'foo' => { 'bar' => 'baz' } } }, data)
+    opts = I18n.backend.class::YAML_LOAD_OPTIONS
+    if opts[:symbolize_names]
+      assert_equal({ :en => { :foo => { :bar => 'baz' } } }, data)
+    else
+      assert_equal({ 'en' => { 'foo' => { 'bar' => 'baz' } } }, data)
+    end
   end
 
   test "simple load_json: loads data from a JSON file" do