Merge pull request #34517 from EByrdS/immutable-enum

Pluralized enum raises error when attempting to modify

activerecord/CHANGELOG.md

+*   Values of enum are frozen, raising an error when attempting to modify them.
+
+    *Emmanuel Byrd*
+
 *   `update_columns` now correctly raises `ActiveModel::MissingAttributeError`
     if the attribute does not exist.
 

activerecord/lib/active_record/enum.rb

@@ -201,6 +201,7 @@ def enum(definitions)
             klass.scope value_method_name, -> { where(attr => value) }
           end
         end
+        enum_values.freeze
       end
     end
 

activerecord/test/cases/enum_test.rb

@@ -409,6 +409,20 @@ def self.name; "Book"; end
     assert_equal ["drafted", "uploaded"], book2.status_change
   end
 
+  test "attempting to modify enum raises error" do
+    e = assert_raises(RuntimeError) do
+      Book.statuses["bad_enum"] = 40
+    end
+
+    assert_match(/can't modify frozen/, e.message)
+
+    e = assert_raises(RuntimeError) do
+      Book.statuses.delete("published")
+    end
+
+    assert_match(/can't modify frozen/, e.message)
+  end
+
   test "declare multiple enums at a time" do
     klass = Class.new(ActiveRecord::Base) do
       self.table_name = "books"