Add current and future scopes for Conference

app/models/conference.rb

@@ -9,6 +9,9 @@ class Conference < ActiveRecord::Base
   has_many :tracks
   has_many :events, through: :tracks
 
+  scope :future, -> { where 'start_date >= ?', Date.today }
+  scope :current, -> { future.first || last }
+
   private
 
   def end_date_is_before_start_date

spec/factories/conferences.rb

@@ -7,5 +7,15 @@ FactoryGirl.define do
     description 'MyText'
     start_date '2014-07-29 21:29:13'
     end_date '2014-07-31 21:29:13'
+
+    factory :past_conference do
+      start_date Date.today - 10.days
+      end_date Date.today - 5.days
+    end
+
+    factory :future_conference do
+      start_date Date.today + 5.days
+      end_date Date.today + 10.days
+    end
   end
 end

spec/models/conference_spec.rb

@@ -39,4 +39,18 @@ RSpec.describe Conference, :type => :model do
   it 'is invalid when the end date is before the start date' do
     expect(build(:conference, start_date: '2014-07-29 21:29:13', end_date: '2014-07-28 01:00:00')).to have_error_on :end_date
   end
+
+  describe '::current' do
+    it 'returns the next conference if there is one' do
+      create :past_conference
+      conference = create :future_conference
+      create :future_conference, start_date: Date.today + 100.years, end_date: Date.today + 150.years
+      expect(Conference.current).to eq conference
+    end
+
+    it 'returns the last conference if there is no future conference' do
+      conference = create :past_conference
+      expect(Conference.current).to eq conference
+    end
+  end
 end