Encapsulate the creation of `Attribute` objects

This will make it less painful to add additional properties, which
should persist across writes, such as `name`.

Conflicts:
	activerecord/lib/active_record/attribute_set.rb

2 files changed, 61 insertions, 1 deletions

diff --git a/activerecord/test/cases/attribute_set_test.rb b/activerecord/test/cases/attribute_set_test.rb
index df35a7b384..35caa0ddab 100644
--- a/activerecord/test/cases/attribute_set_test.rb
+++ b/activerecord/test/cases/attribute_set_test.rb
@@ -35,7 +35,7 @@ module ActiveRecord
       attributes[:bar].value
 
       duped = attributes.dup
-      duped[:foo] = Attribute.from_database(2, Type::Integer.new)
+      duped.write_from_database(:foo, 2)
       duped[:bar].value << 'bar'
 
       assert_equal 1, attributes[:foo].value
@@ -120,6 +120,40 @@ module ActiveRecord
       assert_nil attributes.fetch_value(:bar)
     end
 
+    class MyType
+      def type_cast_from_user(value)
+        return if value.nil?
+        value + " from user"
+      end
+
+      def type_cast_from_database(value)
+        return if value.nil?
+        value + " from database"
+      end
+    end
+
+    test "write_from_database sets the attribute with database typecasting" do
+      builder = AttributeSet::Builder.new(foo: MyType.new)
+      attributes = builder.build_from_database
+
+      assert_nil attributes.fetch_value(:foo)
+
+      attributes.write_from_database(:foo, "value")
+
+      assert_equal "value from database", attributes.fetch_value(:foo)
+    end
+
+    test "write_from_user sets the attribute with user typecasting" do
+      builder = AttributeSet::Builder.new(foo: MyType.new)
+      attributes = builder.build_from_database
+
+      assert_nil attributes.fetch_value(:foo)
+
+      attributes.write_from_user(:foo, "value")
+
+      assert_equal "value from user", attributes.fetch_value(:foo)
+    end
+
     def attributes_with_uninitialized_key
       builder = AttributeSet::Builder.new(foo: Type::Integer.new, bar: Type::Float.new)
       builder.build_from_database(foo: '1.1')
diff --git a/activerecord/test/cases/attribute_test.rb b/activerecord/test/cases/attribute_test.rb
index 57dd2e9a5e..0adf9545b8 100644
--- a/activerecord/test/cases/attribute_test.rb
+++ b/activerecord/test/cases/attribute_test.rb
@@ -99,5 +99,31 @@ module ActiveRecord
       attribute = Attribute.from_database('a value', @type)
       attribute.dup
     end
+
+    class MyType
+      def type_cast_from_user(value)
+        value + " from user"
+      end
+
+      def type_cast_from_database(value)
+        value + " from database"
+      end
+    end
+
+    test "with_value_from_user returns a new attribute with the value from the user" do
+      old = Attribute.from_database("old", MyType.new)
+      new = old.with_value_from_user("new")
+
+      assert_equal "old from database", old.value
+      assert_equal "new from user", new.value
+    end
+
+    test "with_value_from_database returns a new attribute with the value from the database" do
+      old = Attribute.from_user("old", MyType.new)
+      new = old.with_value_from_database("new")
+
+      assert_equal "old from user", old.value
+      assert_equal "new from database", new.value
+    end
   end
 end