Add an initial Track model implementation

app/models/conference.rb

@@ -6,6 +6,8 @@ class Conference < ActiveRecord::Base
   validates :end_date, presence: true
   validate :end_date_is_before_start_date
 
+  has_many :tracks
+
   private
 
   def end_date_is_before_start_date

app/models/track.rb

@@ -0,0 +1,10 @@
+class Track < ActiveRecord::Base
+  belongs_to :conference
+
+  validates :name, presence: true
+  validates :color, presence: true, format: {with: /\A[a-f0-9]{6}\z/i}
+
+  def color=(hex_triplet)
+    write_attribute :color, hex_triplet.gsub(/\A#/,'') if hex_triplet
+  end
+end

db/migrate/20140810172123_create_tracks.rb

@@ -0,0 +1,11 @@
+class CreateTracks < ActiveRecord::Migration
+  def change
+    create_table :tracks do |t|
+      t.string :name, null: false
+      t.string :color, null: false
+      t.references :conference, index: true
+
+      t.timestamps
+    end
+  end
+end

spec/factories/tracks.rb

@@ -0,0 +1,9 @@
+# Read about factories at https://github.com/thoughtbot/factory_girl
+
+FactoryGirl.define do
+  factory :track do
+    name { |n| "Track#{n}" }
+    color '#000000'
+    conference
+  end
+end

spec/models/track_spec.rb

@@ -0,0 +1,19 @@
+require 'rails_helper'
+
+RSpec.describe Track, :type => :model do
+  it 'is invalid without a name' do
+    expect(build(:track, name: '')).to have_error_on :name
+  end
+
+  describe 'color' do
+    it 'must be present' do
+      expect(build(:track, color: '')).to have_error_on :color
+    end
+
+    it 'must be a hex RGB triplet' do
+      expect(build(:track, color: 'foobar')).to have_error_on :color
+      expect(build(:track, color: '000000')).to_not have_error_on :color
+      expect(build(:track, color: '#000000')).to_not have_error_on :color
+    end
+  end
+end