Add schedule interval as attribute of a program

Also, the part of the schedule event is deleted and the length of the event types
changes to the nearest suitable after changing the length of the interval.

This closes #1220

spec/models/program_spec.rb

@@ -13,6 +13,7 @@ describe Program do
     it { is_expected.to have_many(:tracks).dependent(:destroy) }
     it { is_expected.to have_many(:difficulty_levels).dependent(:destroy) }
     it { is_expected.to have_many(:events).dependent(:destroy) }
+    it { is_expected.to have_many(:event_schedules).through(:events) }
     it { is_expected.to have_many(:event_users).through(:events) }
     it { is_expected.to have_many(:speakers).through(:event_users).source(:user) }
 
@@ -32,6 +33,18 @@ describe Program do
 
     it { is_expected.to validate_numericality_of(:rating).is_greater_than_or_equal_to(0).is_less_than_or_equal_to(10).only_integer }
 
+    it { is_expected.to validate_numericality_of(:schedule_interval).is_greater_than_or_equal_to(5).is_less_than_or_equal_to(60) }
+
+    describe 'schedule_interval_divisor_60' do
+      it 'is valid, when schedule_interval is divisor of 60' do
+        expect(build(:program, schedule_interval: 20)).to be_valid
+      end
+
+      it 'is not valid, when schedule_interval is not divisor of 60' do
+        expect(build(:program, schedule_interval: 35)).to_not be_valid
+      end
+    end
+
     describe 'voting_start_date_before_end_date' do
       it 'is valid, when voting_start_date is the same day as voting_end_date' do
         expect(build(:program, voting_start_date: Date.today, voting_end_date: Date.today)).to be_valid
@@ -167,6 +180,34 @@ describe Program do
     end
   end
 
+  describe 'excecutes after_save functions' do
+    it 'and unschedule unfit events if schedule interval was changed' do
+      start_date = program.conference.start_date.to_datetime.change(hour: program.conference.start_hour)
+      create(:event_schedule, event: create(:event, program: program), start_time: start_date.change(min: program.schedule_interval))
+      create(:event_schedule, event: create(:event, program: program), start_time: start_date)
+      expect(program.event_schedules.count).to eq 2
+
+      program.schedule_interval = 10
+      program.save!
+      program.reload
+      expect(program.event_schedules.count).to eq 1
+      expect(program.event_schedules.first.start_time).to eq start_date
+    end
+
+    it 'and change event type length if schedule interval was changed' do
+      program.schedule_interval = 5
+      program.save!
+
+      program.event_types.first.update_attributes length: 5
+      program.event_types.last.update_attributes length: 25
+      create(:event_type, program: program, length: 30)
+
+      program.schedule_interval = 10
+      program.save!
+      expect(program.event_types.pluck(:length).sort).to eq [10, 20, 30]
+    end
+  end
+
   describe 'languages' do
     it "is not valid if languages aren't two letters separated by commas" do
       program.languages = 'eng, De es'