Add Eventserializer tests and fix undefined method `l' for Eventserializer

Solution of no method error pointed by @nishanthvijayan:
http://stackoverflow.com/a/11724935

app/serializers/event_serializer.rb

@@ -5,7 +5,7 @@ class EventSerializer < ActiveModel::Serializer
 
   def date
     t = object.start_time
-    t.blank? ? '' : %{ #{l t, format: :short}#{t.formatted_offset(false)} }
+    t.blank? ? '' : %{ #{I18n.l t, format: :short}#{t.formatted_offset(false)} }
   end
 
   def speaker_ids

spec/serializers/event_serializer_spec.rb

@@ -0,0 +1,58 @@
+require 'spec_helper'
+describe EventSerializer, type: :serializer do
+  let(:event) { create(:event, title: 'Some Talk', abstract: 'Lorem ipsum dolor sit amet') }
+  let(:serializer) { EventSerializer.new(event) }
+
+  context 'event does not have date, speakers, room and tracks assigned' do
+    it 'sets guid, title, length, abstract and type' do
+      expected_json = {
+        event: {
+          guid: event.guid,
+          title: 'Some Talk',
+          length: 30,
+          date: '',
+          language: nil,
+          abstract: '<p>Lorem ipsum dolor sit amet</p>',
+          speaker_ids: [],
+          type: 'Example Event Type',
+          room: nil,
+          track: nil
+        }
+      }.to_json
+
+      expect(serializer.to_json).to eq expected_json
+    end
+  end
+
+  context 'event has date, speakers, room and tracks assigned' do
+    let(:speaker) { create(:speaker) }
+    let(:room) { create(:room) }
+    let(:track) { create(:track) }
+
+    before do
+      event.update_attributes(start_time: Date.new(2014, 03, 04), language: 'English')
+      event.event_users << speaker
+      event.room = room
+      event.track = track
+    end
+
+    it 'sets guid, title, length, abstract, type, date, language, speakers, room and track' do
+      expected_json = {
+        event: {
+          guid: event.guid,
+          title: 'Some Talk',
+          length: 30,
+          date: ' 2014-03-04T00:00:00+0000 ',
+          language: 'English',
+          abstract: '<p>Lorem ipsum dolor sit amet</p>',
+          speaker_ids: [speaker.user.id],
+          type: 'Example Event Type',
+          room: room.guid,
+          track: track.guid
+        }
+      }.to_json
+
+      expect(serializer.to_json).to eq expected_json
+    end
+  end
+end