Fix enum equality

Author: drcapulet

lib/protobuf/enum.rb

@@ -259,6 +259,20 @@ def initialize(parent_class, name, tag)
       super(tag)
     end
 
+    # Custom equality method since otherwise identical values from different
+    # enums will be considered equal by Integer's equality method (or
+    # Fixnum's on Ruby < 2.4.0).
+    #
+    def ==(other)
+      if other.is_a?(Protobuf::Enum)
+        parent_class == other.parent_class && tag == other.tag
+      elsif tag.class == other.class
+        tag == other
+      else
+        false
+      end
+    end
+
     # Overriding the class so ActiveRecord/Arel visitor will visit the enum as an
     # Integer.
     #

spec/lib/protobuf/enum_spec.rb

@@ -21,6 +21,20 @@
       end
     end
 
+    describe '.==' do
+      it 'is true for identical values' do
+        expect(Test::EnumTestType::THREE).to eq(Test::EnumTestType::THREE)
+      end
+
+      it 'is false for different values in the same enum' do
+        expect(Test::EnumTestType::TWO).to_not eq(Test::EnumTestType::THREE)
+      end
+
+      it 'is false for values from different enums' do
+        expect(Test::EnumTestType::THREE).to_not eq(Test::AliasedEnum::THREE)
+      end
+    end
+
     describe '.aliases_allowed?' do
       it 'is false when the option is not set' do
         expect(Test::EnumTestType.aliases_allowed?).to be false