Convert protected_environments to an array of strings

  These changes prevent ignoring environments name of which is a `Symbol`
  ```
  config.active_record.protected_environments = ['staging', :production]
  ```

1 files changed, 16 insertions, 14 deletions

diff --git a/activerecord/lib/active_record/model_schema.rb b/activerecord/lib/active_record/model_schema.rb
index 1941d3d5ea..773b0f6cde 100644
--- a/activerecord/lib/active_record/model_schema.rb
+++ b/activerecord/lib/active_record/model_schema.rb
@@ -87,19 +87,6 @@ module ActiveRecord
     # Sets the name of the internal metadata table.
 
     ##
-    # :singleton-method: protected_environments
-    # :call-seq: protected_environments
-    #
-    # The array of names of environments where destructive actions should be prohibited. By default,
-    # the value is <tt>["production"]</tt>.
-
-    ##
-    # :singleton-method: protected_environments=
-    # :call-seq: protected_environments=(environments)
-    #
-    # Sets an array of names of environments where destructive actions should be prohibited.
-
-    ##
     # :singleton-method: pluralize_table_names
     # :call-seq: pluralize_table_names
     #
@@ -122,9 +109,9 @@ module ActiveRecord
       class_attribute :table_name_suffix, instance_writer: false, default: ""
       class_attribute :schema_migrations_table_name, instance_accessor: false, default: "schema_migrations"
       class_attribute :internal_metadata_table_name, instance_accessor: false, default: "ar_internal_metadata"
-      class_attribute :protected_environments, instance_accessor: false, default: [ "production" ]
       class_attribute :pluralize_table_names, instance_writer: false, default: true
 
+      self.protected_environments = ["production"]
       self.inheritance_column = "type"
       self.ignored_columns = [].freeze
 
@@ -238,6 +225,21 @@ module ActiveRecord
         (parents.detect { |p| p.respond_to?(:table_name_suffix) } || self).table_name_suffix
       end
 
+      # The array of names of environments where destructive actions should be prohibited. By default,
+      # the value is <tt>["production"]</tt>.
+      def protected_environments
+        if defined?(@protected_environments)
+          @protected_environments
+        else
+          superclass.protected_environments
+        end
+      end
+
+      # Sets an array of names of environments where destructive actions should be prohibited.
+      def protected_environments=(environments)
+        @protected_environments = environments.map(&:to_s)
+      end
+
       # Defines the name of the table column which will store the class name on single-table
       # inheritance situations.
       #