Deprecate Date#to_time_in_current_zone

The to_time_in_current_zone method doesn't match the naming of the methods
for converting to ActiveSupport::TimeWithZone on Time and DateTime. Since
DateTime inherits from Date that has led to confusion with some users
using the to_time_in_current_zone method with DateTime instances and having
the time part dropped and the UTC offset lost.

This commit fixes this by deprecating the old method and adding a new
in_time_zone method which matches the naming for DateTime and Time. This
should prevent accidently dropping times and UTC offsets when converting
DateTime instances to ActiveSupport::TimeWithZone.

activesupport/CHANGELOG.md

 ## Rails 4.0.0 (unreleased) ##
 
+*   Deprecate `Date#to_time_in_current_zone` and add `Date#in_time_zone`. *Andrew White*
+
 *   Add `String#in_time_zone` method to convert a string to an ActiveSupport::TimeWithZone. *Andrew White*
 
 *   Deprecate `ActiveSupport::BasicObject` in favor of `ActiveSupport::ProxyObject`.

activesupport/lib/active_support/core_ext/date/calculations.rb

@@ -53,19 +53,19 @@ def current
   # Converts Date to a Time (or DateTime if necessary) with the time portion set to the beginning of the day (0:00)
   # and then subtracts the specified number of seconds.
   def ago(seconds)
-    to_time_in_current_zone.since(-seconds)
+    in_time_zone.since(-seconds)
   end
 
   # Converts Date to a Time (or DateTime if necessary) with the time portion set to the beginning of the day (0:00)
   # and then adds the specified number of seconds
   def since(seconds)
-    to_time_in_current_zone.since(seconds)
+    in_time_zone.since(seconds)
   end
   alias :in :since
 
   # Converts Date to a Time (or DateTime if necessary) with the time portion set to the beginning of the day (0:00)
   def beginning_of_day
-    to_time_in_current_zone
+    in_time_zone
   end
   alias :midnight :beginning_of_day
   alias :at_midnight :beginning_of_day
@@ -73,7 +73,7 @@ def beginning_of_day
 
   # Converts Date to a Time (or DateTime if necessary) with the time portion set to the end of the day (23:59:59)
   def end_of_day
-    to_time_in_current_zone.end_of_day
+    in_time_zone.end_of_day
   end
   alias :at_end_of_day :end_of_day
 

activesupport/lib/active_support/core_ext/date/conversions.rb

@@ -79,6 +79,6 @@ def to_time(form = :local)
   end
 
   def xmlschema
-    to_time_in_current_zone.xmlschema
+    in_time_zone.xmlschema
   end
 end

activesupport/lib/active_support/core_ext/date/zones.rb

@@ -2,14 +2,36 @@
 require 'active_support/core_ext/time/zones'
 
 class Date
+  # *DEPRECATED*: Use +Date#in_time_zone+ instead.
+  #
   # Converts Date to a TimeWithZone in the current zone if <tt>Time.zone</tt> or
   # <tt>Time.zone_default</tt> is set, otherwise converts Date to a Time via
   # Date#to_time.
   def to_time_in_current_zone
+    ActiveSupport::Deprecation.warn 'Date#to_time_in_current_zone is deprecated. Use Date#in_time_zone instead', caller
+
     if ::Time.zone
       ::Time.zone.local(year, month, day)
     else
       to_time
     end
   end
+
+  # Converts Date to a TimeWithZone in the current zone if Time.zone or Time.zone_default
+  # is set, otherwise converts Date to a Time via Date#to_time
+  #
+  #   Time.zone = 'Hawaii'         # => 'Hawaii'
+  #   Date.new(2000).in_time_zone  # => Sat, 01 Jan 2000 00:00:00 HST -10:00
+  #
+  # You can also pass in a TimeZone instance or string that identifies a TimeZone as an argument,
+  # and the conversion will be based on that zone instead of <tt>Time.zone</tt>.
+  #
+  #   Date.new(2000).in_time_zone('Alaska')  # => Sat, 01 Jan 2000 00:00:00 AKST -09:00
+  def in_time_zone(zone = ::Time.zone)
+    if zone
+      ::Time.find_zone!(zone).local(year, month, day)
+    else
+      to_time
+    end
+  end
 end

activesupport/test/core_ext/date_ext_test.rb

@@ -354,3 +354,11 @@ def test_can_freeze_twice
     end
   end
 end
+
+class DateExtConversionsTest < ActiveSupport::TestCase
+  def test_to_time_in_current_zone_is_deprecated
+    assert_deprecated(/to_time_in_current_zone/) do
+      Date.new(2012,6,7).to_time_in_current_zone
+    end
+  end
+end