Add scenario to RelatedContent model spec to check opposite related content creation

app/models/related_content.rb

@@ -1,6 +1,7 @@
 class RelatedContent < ActiveRecord::Base
   belongs_to :parent_relationable, polymorphic: true
   belongs_to :child_relationable, polymorphic: true
+  has_one :opposite_related_content, class_name: 'RelatedContent', foreign_key: :related_content_id
 
   validates :parent_relationable_id, presence: true
   validates :parent_relationable_type, presence: true
@@ -8,4 +9,13 @@ class RelatedContent < ActiveRecord::Base
   validates :child_relationable_type, presence: true
   validates :parent_relationable_id, uniqueness: { scope: [:parent_relationable_type, :child_relationable_id, :child_relationable_type] }
 
+  after_create :create_opposite_related_content, unless: proc { opposite_related_content.present? }
+
+  private
+
+  def create_opposite_related_content
+    related_content = RelatedContent.create!(opposite_related_content: self, parent_relationable: child_relationable, child_relationable: parent_relationable)
+    self.opposite_related_content = related_content
+  end
+
 end

spec/models/relation_spec.rb

@@ -23,4 +23,19 @@ describe RelatedContent do
     expect(new_related_content).not_to be_valid
   end
 
+  describe 'create_opposite_related_content' do
+    let(:parent_relationable) { create(:proposal) }
+    let(:child_relationable) { create(:debate) }
+    let(:related_content) { build(:related_content, parent_relationable: parent_relationable, child_relationable: child_relationable) }
+
+    it 'creates an opposite related_content' do
+      expect { related_content.save }.to change { RelatedContent.count }.by(2)
+      expect(related_content.opposite_related_content.child_relationable_id).to eq(parent_relationable.id)
+      expect(related_content.opposite_related_content.child_relationable_type).to eq(parent_relationable.class.name)
+      expect(related_content.opposite_related_content.parent_relationable_id).to eq(child_relationable.id)
+      expect(related_content.opposite_related_content.parent_relationable_type).to eq(child_relationable.class.name)
+      expect(related_content.opposite_related_content.opposite_related_content.id).to eq(related_content.id)
+    end
+  end
+
 end