Change behavior of Attribute#== method

By changing Coercer#== and DefaultValue#== methods, we allow
Attribute#== to actually compare objects now (before, every comparison
would return `false` because of different instances of DefaultValue
model in options[:default_value] key.

lib/virtus/attribute/default_value.rb

@@ -7,6 +7,8 @@ class Attribute
     class DefaultValue
       extend DescendantsTracker
 
+      include Equalizer.new(inspect) << :value
+
       # Builds a default value instance
       #
       # @return [Virtus::Attribute::DefaultValue]

lib/virtus/coercer.rb

@@ -3,6 +3,7 @@ module Virtus
   # Abstract coercer class
   #
   class Coercer
+    include Equalizer.new(inspect) << :primitive << :type
 
     # @api private
     attr_reader :primitive, :type

spec/unit/virtus/attribute/comparison_spec.rb

@@ -3,12 +3,9 @@
 describe Virtus::Attribute, '#== (defined by including Virtus::Equalizer)' do
   let(:attribute) { described_class.build(String, :name => :name) }
 
-  # Currently that's the way it works and it happens because default_value objects
-  # don't have equalizer, resulting in  attributes object mismatch.
-  # This behavior (and a spec) will need a change in future.
-  it 'returns false when attributes have same type and options' do
+  it 'returns true when attributes have same type and options' do
     equal_attribute = described_class.build(String, :name => :name)
-    expect(attribute == equal_attribute).to be_falsey
+    expect(attribute == equal_attribute).to be_truthy
   end
 
   it 'returns false when attributes have different type' do

spec/unit/virtus/attribute_set/append_spec.rb

@@ -38,10 +38,10 @@
 
     it { is_expected.to equal(object) }
 
-    it 'replaces the original attribute' do
-      expect { subject }.to change { object.to_a }.
-        from(attributes).
-        to([ attribute ])
+    it "replaces the original attribute object" do
+      expect { subject }.to change { object.to_a.map(&:__id__) }.
+      from(attributes.map(&:__id__)).
+      to([attribute.__id__])
     end
   end
 end

spec/unit/virtus/attribute_set/element_set_spec.rb

@@ -37,20 +37,28 @@
 
     it { is_expected.to equal(attribute) }
 
-    it 'replaces the original attribute' do
-      expect { subject }.to change { object.to_a }.from(attributes).to([ attribute ])
+    it "replaces the original attribute object" do
+      expect { subject }.to change { object.to_a.map(&:__id__) }.
+      from(attributes.map(&:__id__)).
+      to([attribute.__id__])
     end
 
-    it 'allows #[] to access the attribute with a symbol' do
-      expect { subject }.to change { object['name'] }.from(original).to(attribute)
+    it 'allows #[] to access the attribute with a string' do
+      expect { subject }.to change { object['name'].__id__ }.
+      from(original.__id__).
+      to(attribute.__id__)
     end
 
-    it 'allows #[] to access the attribute with a string' do
-      expect { subject }.to change { object[:name] }.from(original).to(attribute)
+    it 'allows #[] to access the attribute with a symbol' do
+      expect { subject }.to change { object[:name].__id__ }.
+      from(original.__id__).
+      to(attribute.__id__)
     end
 
     it 'allows #reset to track overridden attributes' do
-      expect { subject }.to change { object.reset.to_a }.from(attributes).to([ attribute ])
+      expect { subject }.to change { object.reset.to_a.map(&:__id__) }.
+      from(attributes.map(&:__id__)).
+      to([attribute.__id__])
     end
   end
 end

spec/unit/virtus/attribute_set/merge_spec.rb

@@ -21,12 +21,14 @@
 
   context 'with a duplicate attribute' do
     let(:attributes) { [Virtus::Attribute.build(String, :name => name)] }
-    let(:attribute)  { Virtus::Attribute.build(String, :name => name) }
+    let(:attribute)  {  Virtus::Attribute.build(String, :name => name) }
 
     it { is_expected.to equal(object) }
 
-    it 'replaces the original attribute' do
-      expect { subject }.to change { object.to_a }.from(attributes).to([attribute])
+    it "replaces the original attribute object" do
+      expect { subject }.to change { object.to_a.map(&:__id__) }.
+      from(attributes.map(&:__id__)).
+      to([attribute.__id__])
     end
   end
 end