Added validation in EventSchedule model and test in event_schedule_spec

EventSchedule start time should be in hours range of the conference.Therefore it adds validation on start_time attribute of event schedule model. It also adds test for the same.

spec/models/event_schedule_spec.rb

@@ -1,6 +1,7 @@
 require 'spec_helper'
 
 describe EventSchedule do
+  let(:conference) { create(:conference) }
 
   describe 'association' do
     it { should belong_to(:schedule) }
@@ -17,5 +18,32 @@ describe EventSchedule do
     it { is_expected.to validate_presence_of(:event) }
     it { is_expected.to validate_presence_of(:room) }
     it { is_expected.to validate_presence_of(:start_time) }
+
+    describe '#start_after_end_hour' do
+      context 'is invalid' do
+        it 'when event schedule start_time is after the conference end_hour, and returns an error message' do
+          new_scheduled_event = build(:event_scheduled, program: conference.program, hour: conference.start_date + conference.end_hour.hours + 1.hour)
+          expect(new_scheduled_event.valid?).to eq false
+          expect(new_scheduled_event.event_schedules.first.errors[:start_time]).to eq ["can't be after the conference end hour (#{conference.end_hour})"]
+        end
+      end
+
+      context 'is valid' do
+        it 'when event schedule start_time is between the conference end_hour and start_hour' do
+          new_scheduled_event = build(:event_scheduled, program: conference.program, hour: conference.start_date + conference.end_hour.hours - 1.hour)
+          expect(new_scheduled_event.valid?).to eq true
+        end
+      end
+    end
+
+    describe '#start_before_start_hour' do
+      context 'is invalid' do
+        it 'when event schedule start_time is before the conference start_hour, and returns an error message' do
+          new_scheduled_event = build(:event_scheduled, program: conference.program, hour: conference.start_date)
+          expect(new_scheduled_event.valid?).to eq false
+          expect(new_scheduled_event.event_schedules.first.errors[:start_time]).to eq ["can't be before the conference start hour (#{conference.start_hour})"]
+        end
+      end
+    end
   end
 end