Add reference source and target behaviour

app/models/comment.rb

@@ -14,6 +14,7 @@ class Comment < ApplicationRecord
   include Diaspora::Taggable
   include Diaspora::Likeable
   include Diaspora::MentionsContainer
+  include Reference::Source
 
   acts_as_taggable_on :tags
   extract_tags_from :text

app/models/message.rb

@@ -5,6 +5,8 @@ class Message < ApplicationRecord
   include Diaspora::Fields::Guid
   include Diaspora::Fields::Author
 
+  include Reference::Source
+
   belongs_to :conversation, touch: true
 
   delegate :name, to: :author, prefix: true

app/models/reference.rb

@@ -4,4 +4,20 @@ class Reference < ApplicationRecord
   belongs_to :source, polymorphic: true
   belongs_to :target, polymorphic: true
   validates :target_id, uniqueness: {scope: %i[target_type source_id source_type]}
+
+  module Source
+    extend ActiveSupport::Concern
+
+    included do
+      has_many :references, as: :source, dependent: :destroy
+    end
+  end
+
+  module Target
+    extend ActiveSupport::Concern
+
+    included do
+      has_many :referenced_by, as: :target, class_name: "Reference", dependent: :destroy
+    end
+  end
 end

app/models/status_message.rb

@@ -7,6 +7,9 @@
 class StatusMessage < Post
   include Diaspora::Taggable
 
+  include Reference::Source
+  include Reference::Target
+
   include PeopleHelper
 
   acts_as_taggable_on :tags

spec/models/comment_spec.rb

@@ -10,6 +10,7 @@ describe Comment, type: :model do
   let(:comment_alice) { alice.comment!(status_bob, "why so formal?") }
 
   it_behaves_like "it is mentions container"
+  it_behaves_like "a reference source"
 
   describe "#destroy" do
     it "should delete a participation" do

spec/models/message_spec.rb

@@ -52,4 +52,6 @@ describe Message, type: :model do
       expect(conf.reload.unread).to eq(1)
     end
   end
+
+  it_behaves_like "a reference source"
 end

spec/models/status_message_spec.rb

@@ -147,6 +147,9 @@ describe StatusMessage, type: :model do
     end
   end
 
+  it_behaves_like "a reference source"
+  it_behaves_like "a reference target"
+
   describe "#nsfw" do
     it "returns MatchObject (true) if the post contains #nsfw (however capitalised)" do
       status = FactoryGirl.build(:status_message, text: "This message is #nSFw")

spec/shared_behaviors/references.rb

@@ -0,0 +1,33 @@
+# frozen_string_literal: true
+
+shared_examples_for "a reference source" do
+  let!(:source) { FactoryGirl.create(described_class.to_s.underscore.to_sym) }
+  let!(:reference) { FactoryGirl.create(:reference, source: source) }
+
+  describe "references" do
+    it "returns the references" do
+      expect(source.references).to match_array([reference])
+    end
+
+    it "destroys the reference when the source is destroyed" do
+      source.destroy
+      expect(Reference.where(id: reference.id)).not_to exist
+    end
+  end
+end
+
+shared_examples_for "a reference target" do
+  let!(:target) { FactoryGirl.create(described_class.to_s.underscore.to_sym) }
+  let!(:reference) { FactoryGirl.create(:reference, target: target) }
+
+  describe "referenced_by" do
+    it "returns the references where the target is referenced" do
+      expect(target.referenced_by).to match_array([reference])
+    end
+
+    it "destroys the reference when the target is destroyed" do
+      target.destroy
+      expect(Reference.where(id: reference.id)).not_to exist
+    end
+  end
+end