Don't calculate for days in next month when start day < 28

Fixes #171

lib/ice_cube/validations/lock.rb

@@ -62,8 +62,8 @@ def validate_day_lock(time, schedule)
       if value && value > 0
         until_next_month = days_in_month + sleeps
       else
-        until_next_month = TimeUtil.days_to_next_month(date) + sleeps
-        until_next_month -= month_overflow
+        until_next_month = start < 28 ? days_in_month : TimeUtil.days_to_next_month(date)
+        until_next_month += sleeps - month_overflow
       end
 
       sleeps >= 0 ? sleeps : until_next_month

spec/examples/validated_rule_spec.rb

@@ -21,6 +21,13 @@
         rule.next_time(first + 1, schedule, nil).should == Time.new(2013, 3, 25, 0, 0, 0)
       end
 
+      it 'should return the next month near end of longer month [#171]' do
+        schedule = IceCube::Schedule.new(Date.new 2013, 1, 1)
+        [27, 28, 29, 30, 31].each do |day|
+          rule.next_time(Time.new(2013, 1, day), schedule, nil).should == Time.new(2013, 2, 1)
+        end
+      end
+
       context "DST edge" do
         before { Time.zone = "Europe/London" }
         let(:first) { Time.zone.parse("Sun, 31 Mar 2013 00:00:00 GMT +00:00") }