Add PushNotification#to

app/models/push_notification.rb

@@ -3,4 +3,8 @@ class PushNotification < ActiveRecord::Base
   belongs_to :device_token, foreign_key: 'device_token_id'
 
   validates :event, :device_token, presence: true
+
+  def to
+    device_token.token
+  end
 end

spec/models/push_notification_spec.rb

@@ -13,4 +13,13 @@ RSpec.describe PushNotification do
     it { is_expected.to have_db_column(:event_id) }
     it { is_expected.to have_db_column(:device_token_id) }
   end
+
+  describe "#to" do
+    let(:device_token) { Fabricate.build(:device_token, token: 'token') }
+    let(:push_notification) { described_class.new(device_token: device_token) }
+
+    it 'returns the associated DeviceToken\'s token' do
+      expect(push_notification.to).to eq('token')
+    end
+  end
 end