Add test to make sure this method will not be removed again

activemodel/lib/active_model/attributes.rb

@@ -120,6 +120,7 @@ module ActiveModel
     end
 
     private
+      # Writes a value to an attribute by name following aliases if necessary.
       def write_attribute(attr_name, value)
         name = attr_name.to_s
         name = self.class.attribute_aliases[name] || name
@@ -132,6 +133,7 @@ module ActiveModel
       end
       alias :attribute= :_write_attribute
 
+      # Reads a value from an attribute by name following aliases if necessary.
       def read_attribute(attr_name)
         name = attr_name.to_s
         name = self.class.attribute_aliases[name] || name

activemodel/test/cases/attributes_test.rb

@@ -14,6 +14,19 @@ module ActiveModel
       attribute :string_with_default, :string, default: "default string"
       attribute :date_field, :date, default: -> { Date.new(2016, 1, 1) }
       attribute :boolean_field, :boolean
+
+      alias_attribute :integer, :integer_field
+      alias_attribute :string, :string_field
+
+      def method_that_writes_to_an_attribute
+        value = read_attribute(:integer_field)
+        write_attribute(:string_field, value.to_s)
+      end
+
+      def method_that_writes_to_an_attribute_using_aliases
+        value = read_attribute(:integer)
+        write_attribute(:string, value.to_s)
+      end
     end
 
     class ChildModelForAttributesTest < ModelForAttributesTest
@@ -129,5 +142,19 @@ module ActiveModel
       assert data.frozen?
       assert_raise(FrozenError) { data.integer_field = 1 }
     end
+
+    test "attributes can be read and written using the public API" do
+      data = ModelForAttributesTest.new(integer_field: 20)
+      data.method_that_writes_to_an_attribute
+
+      assert_equal "20", data.string_field
+    end
+
+    test "attributes can be read and written using the public API even with aliases" do
+      data = ModelForAttributesTest.new(integer: 20)
+      data.method_that_writes_to_an_attribute
+
+      assert_equal "20", data.string
+    end
   end
 end