Returns Milestone::Upcoming for boards with this milestone

app/models/board.rb

 class Board < ActiveRecord::Base
   belongs_to :project
+  belongs_to :milestone
 
   has_many :lists, -> { order(:list_type, :position) }, dependent: :delete_all
-  belongs_to :milestone
 
   validates :name, :project, presence: true
 
   def done_list
     lists.merge(List.done).take
   end
+
+  def milestone
+    if milestone_id === Milestone::Upcoming.id
+      Milestone::Upcoming
+    else
+      super
+    end
+  end
 end

spec/models/board_spec.rb

@@ -3,6 +3,8 @@ require 'rails_helper'
 describe Board do
   describe 'relationships' do
     it { is_expected.to belong_to(:project) }
+    it { is_expected.to belong_to(:milestone) }
+
     it { is_expected.to have_many(:lists).order(list_type: :asc, position: :asc).dependent(:delete_all) }
   end
 
@@ -10,4 +12,27 @@ describe Board do
     it { is_expected.to validate_presence_of(:name) }
     it { is_expected.to validate_presence_of(:project) }
   end
+
+  describe 'milestone' do
+    subject { described_class.new }
+
+    it 'returns Milestone::Upcoming for upcoming milestone id' do
+      subject.milestone_id = Milestone::Upcoming.id
+
+      expect(subject.milestone).to eq Milestone::Upcoming
+    end
+
+    it 'returns milestone for valid milestone id' do
+      milestone = create(:milestone)
+      subject.milestone_id = milestone.id
+
+      expect(subject.milestone).to eq milestone
+    end
+
+    it 'returns nil for invalid milestone id' do
+      subject.milestone_id = -1
+
+      expect(subject.milestone).to be_nil
+    end
+  end
 end