Removed duplicate methods date_range_string and date_string.

Added tests for date_string function

corrections in the test

app/helpers/application_helper.rb

@@ -1,4 +1,39 @@
 module ApplicationHelper
+  ##
+  # Returns a string build from the start and end date of the given conference.
+  #
+  # If the conference is only one day long
+  # * %B %d %Y (January 17 2014)
+  # If the conference starts and ends in the same month and year
+  # * %B %d - %d, %Y (January 17 - 21 2014)
+  # If the conference ends in another month but in the same year
+  # * %B %d - %B %d, %Y (January 31 - February 02 2014)
+  # All other cases
+  # * %B %d, %Y - %B %d, %Y (December 30, 2013 - January 02, 2014)
+  def date_string(start_date, end_date)
+    startstr = 'Unknown - '
+    endstr = 'Unknown'
+    # When the conference is in the same month
+    if start_date.month == end_date.month && start_date.year == end_date.year
+      if start_date.day == end_date.day
+        startstr = start_date.strftime('%B %d')
+        endstr = end_date.strftime(' %Y')
+      else
+        startstr = start_date.strftime('%B %d - ')
+        endstr = end_date.strftime('%d, %Y')
+      end
+    elsif start_date.month != end_date.month && start_date.year == end_date.year
+      startstr = start_date.strftime('%B %d - ')
+      endstr = end_date.strftime('%B %d, %Y')
+    else
+      startstr = start_date.strftime('%B %d, %Y - ')
+      endstr = end_date.strftime('%B %d, %Y')
+    end
+
+    result = startstr + endstr
+    result
+  end
+
   ##
   # Checks if the voting has already started, or if it has already ended
   #