From bc153cff9156e7e19b3587f0bb8062d238644b1d Mon Sep 17 00:00:00 2001
From: Sean Griffin <sean@thoughtbot.com>
Date: Fri, 15 Aug 2014 13:37:53 -0600
Subject: [PATCH] Implement `==` on `Type::Value` and `Attribute`

This was a small self contained piece of the refactoring that I am
working on, which required these objects to be comparable.
---
 activerecord/lib/active_record/attribute.rb  |  7 +++++
 activerecord/lib/active_record/type/value.rb |  7 +++++
 activerecord/test/cases/attribute_test.rb    | 30 ++++++++++++++++++++
 activerecord/test/cases/types_test.rb        |  6 ++++
 4 files changed, 50 insertions(+)

diff --git a/activerecord/lib/active_record/attribute.rb b/activerecord/lib/active_record/attribute.rb
index 6d38224830..15cbbcff68 100644
--- a/activerecord/lib/active_record/attribute.rb
+++ b/activerecord/lib/active_record/attribute.rb
@@ -62,6 +62,13 @@ def initialized?
       true
     end
 
+    def ==(other)
+      self.class == other.class &&
+        name == other.name &&
+        value_before_type_cast == other.value_before_type_cast &&
+        type == other.type
+    end
+
     protected
 
     def initialize_dup(other)
diff --git a/activerecord/lib/active_record/type/value.rb b/activerecord/lib/active_record/type/value.rb
index 475e130013..9456a4a56c 100644
--- a/activerecord/lib/active_record/type/value.rb
+++ b/activerecord/lib/active_record/type/value.rb
@@ -76,6 +76,13 @@ def changed_in_place?(*)
         false
       end
 
+      def ==(other)
+        self.class == other.class &&
+          precision == other.precision &&
+          scale == other.scale &&
+          limit == other.limit
+      end
+
       private
 
       def type_cast(value)
diff --git a/activerecord/test/cases/attribute_test.rb b/activerecord/test/cases/attribute_test.rb
index 91f6aee931..7b325abf1d 100644
--- a/activerecord/test/cases/attribute_test.rb
+++ b/activerecord/test/cases/attribute_test.rb
@@ -138,5 +138,35 @@ def type_cast_from_database(value)
     test "uninitialized attributes have no value" do
       assert_nil Attribute.uninitialized(:foo, nil).value
     end
+
+    test "attributes equal other attributes with the same constructor arguments" do
+      first = Attribute.from_database(:foo, 1, Type::Integer.new)
+      second = Attribute.from_database(:foo, 1, Type::Integer.new)
+      assert_equal first, second
+    end
+
+    test "attributes do not equal attributes with different names" do
+      first = Attribute.from_database(:foo, 1, Type::Integer.new)
+      second = Attribute.from_database(:bar, 1, Type::Integer.new)
+      assert_not_equal first, second
+    end
+
+    test "attributes do not equal attributes with different types" do
+      first = Attribute.from_database(:foo, 1, Type::Integer.new)
+      second = Attribute.from_database(:foo, 1, Type::Float.new)
+      assert_not_equal first, second
+    end
+
+    test "attributes do not equal attributes with different values" do
+      first = Attribute.from_database(:foo, 1, Type::Integer.new)
+      second = Attribute.from_database(:foo, 2, Type::Integer.new)
+      assert_not_equal first, second
+    end
+
+    test "attributes do not equal attributes of other classes" do
+      first = Attribute.from_database(:foo, 1, Type::Integer.new)
+      second = Attribute.from_user(:foo, 1, Type::Integer.new)
+      assert_not_equal first, second
+    end
   end
 end
diff --git a/activerecord/test/cases/types_test.rb b/activerecord/test/cases/types_test.rb
index 5c54812f30..db4f78d354 100644
--- a/activerecord/test/cases/types_test.rb
+++ b/activerecord/test/cases/types_test.rb
@@ -149,6 +149,12 @@ def test_string_to_time_with_timezone
         end
       end
 
+      def test_type_equality
+        assert_equal Type::Value.new, Type::Value.new
+        assert_not_equal Type::Value.new, Type::Integer.new
+        assert_not_equal Type::Value.new(precision: 1), Type::Value.new(precision: 2)
+      end
+
       if current_adapter?(:SQLite3Adapter)
         def test_binary_encoding
           type = SQLite3Binary.new
-- 
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