1 files changed, 22 insertions, 3 deletions
diff --git a/activemodel/test/cases/attribute_assignment_test.rb b/activemodel/test/cases/attribute_assignment_test.rb
index 3336691841..12e007292a 100644
--- a/activemodel/test/cases/attribute_assignment_test.rb
+++ b/activemodel/test/cases/attribute_assignment_test.rb
@@ -23,13 +23,32 @@ class AttributeAssignmentTest < ActiveModel::TestCase
   class ErrorFromAttributeWriter < StandardError
   end
 
-  class ProtectedParams < ActiveSupport::HashWithIndifferentAccess
+  class ProtectedParams
+    attr_accessor :permitted
+    alias :permitted? :permitted
+
+    delegate :keys, :key?, :has_key?, :empty?, to: :@parameters
+
+    def initialize(attributes)
+      @parameters = attributes.with_indifferent_access
+      @permitted = false
+    end
+
     def permit!
       @permitted = true
+      self
+    end
+
+    def [](key)
+      @parameters[key]
+    end
+
+    def to_h
+      @parameters
     end
 
-    def permitted?
-      @permitted ||= false
+    def stringify_keys
+      dup
     end
 
     def dup