Introduce CallForParticipation status predicates

Introduce the #open? #closed? and #in_progress? methods for the
CallForParticipation model.

app/models/call_for_participation.rb

@@ -1,3 +1,14 @@
 class CallForParticipation < ActiveRecord::Base
   belongs_to :conference
+  def open?
+    self.opens_at.present? and self.opens_at < Time.now
+  end
+
+  def closed?
+    self.closes_at.present? and self.closes_at < Time.now
+  end
+
+  def in_progress?
+    open? and not closed?
+  end
 end

spec/models/call_for_participation_spec.rb

@@ -1,9 +1,73 @@
 require 'rails_helper'
 
 RSpec.describe CallForParticipation, type: :model do
+  let(:cfp) { build :call_for_participation }
+
   it 'belongs to a conference' do
     conference = create :conference
     cfp = create(:call_for_participation, conference_id: conference.id)
     expect(CallForParticipation.find(cfp.id).conference).to eq conference
   end
+
+  describe '#open?' do
+    it 'returns true when the CFP has an opens_at date in the past' do
+      cfp.opens_at = 10.minutes.ago
+
+      expect(cfp.open?).to be true
+    end
+
+    it 'returns false when the CFP has no opens_at date' do
+      cfp.opens_at = nil
+
+      expect(cfp.open?).to be false
+    end
+
+    it 'returns false when the CFP has an opens_at date in the future' do
+      cfp.opens_at = 10.minutes.from_now
+
+      expect(cfp.open?).to be false
+    end
+  end
+
+  describe '#closed?' do
+    it 'returns true when the CFP has a closes_at date in the past' do
+      cfp.closes_at = 10.minutes.ago
+
+      expect(cfp.closed?).to be true
+    end
+
+    it 'returns false when the CFP has no closes_at date' do
+      cfp.closes_at = nil
+
+      expect(cfp.closed?).to be false
+    end
+
+    it 'returns false when the CFP has a closes_at date in the future' do
+      cfp.closes_at = 10.minutes.from_now
+
+      expect(cfp.closed?).to be false
+    end
+  end
+
+  describe '#in_progress?' do
+    it 'returns true when the CFP has been opened and has not been closed' do
+      expect(cfp).to receive(:open?) { true }
+      expect(cfp).to receive(:closed?) { false }
+
+      expect(cfp.in_progress?).to be true
+    end
+
+    it 'returns false when the CFP has not been opened' do
+      expect(cfp).to receive(:open?) { false }
+
+      expect(cfp.in_progress?).to be false
+    end
+
+    it 'returns false when the CFP has been closed' do
+      expect(cfp).to receive(:open?) { true }
+      expect(cfp).to receive(:closed?) { true }
+
+      expect(cfp.in_progress?).to be false
+    end
+  end
 end