Remove User#at_midnight

Replace it with a class called DateUtils with a method called
`#midnight_for` that takes a preference instance and date to convert to
midnight.

app/models/preference.rb

@@ -22,6 +22,6 @@ class Preference < ActiveRecord::Base
       raise ArgumentError.new("Bad argument type:#{s.class}")
     end
 
-    user.at_midnight(date)
+    DateUtils::midnight_for(self, date)
   end
 end

app/models/todo.rb

@@ -260,7 +260,7 @@ class Todo < ActiveRecord::Base
       activate
     else
       # parse Date objects into the proper timezone
-      date = user.at_midnight(date) if (date.is_a? Date)
+      date = DateUtils.midnight_for(user.prefs, date) if (date.is_a? Date)
 
       # show_from needs to be set before state_change because of "bug" in aasm.
       # If show_from is not set, the todo will not validate and thus aasm will not save

app/models/user.rb

@@ -167,10 +167,6 @@ class User < ActiveRecord::Base
     time.midnight
   end
 
-  def at_midnight(date)
-    return ActiveSupport::TimeZone[prefs.time_zone].local(date.year, date.month, date.day, 0, 0, 0)
-  end
-
   def generate_token
     self.token = Digest::SHA1.hexdigest "#{Time.now.to_i}#{rand}"
   end

lib/date_utils.rb

@@ -0,0 +1,5 @@
+class DateUtils
+  def self.midnight_for(prefs, date)
+    ActiveSupport::TimeZone[prefs.time_zone].local(date.year, date.month, date.day, 0, 0, 0)
+  end
+end

test/controllers/recurring_todos_controller_test.rb

@@ -117,7 +117,9 @@ class RecurringTodosControllerTest < ActionController::TestCase
     new_todo = Todo.where(:recurring_todo_id => 5).first
 
     # due date should be the target_date
-    assert_equal users(:admin_user).at_midnight(Date.new(target_date.year, target_date.month, target_date.day)), new_todo.due
+    user = users(:admin_user)
+    target_date = Date.new(target_date.year, target_date.month, target_date.day)
+    assert_equal DateUtils.midnight_for(user.prefs, target_date), new_todo.due
 
     # show_from should be nil since now+4.days-10.days is in the past
     assert_equal nil, new_todo.show_from

test/models/preference_test.rb

@@ -20,7 +20,8 @@ class PreferenceTest < ActiveSupport::TestCase
   end
   
   def test_parse_date
-    assert_equal @admin_user.at_midnight(Date.new(2007, 5, 20)).to_s, @admin_user.preference.parse_date('20/5/2007').to_s
+    date = Time.new(2007, 05, 20).in_time_zone(@admin_user.preference.time_zone).at_midnight
+    assert_equal date.to_s, @admin_user.preference.parse_date('20/5/2007').to_s
   end
   
   def test_parse_date_returns_nil_if_string_is_empty