Cater for DST changes when converting Times to DateTimes. Closes #10068 [gbuesing]

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@8076 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

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

@@ -5,6 +5,16 @@ module ActiveSupport #:nodoc:
     module DateTime #:nodoc:
       # Enables the use of time calculations within DateTime itself
       module Calculations
+        def self.included(base) #:nodoc:
+          base.extend ClassMethods
+        end
+
+        module ClassMethods
+          # DateTimes aren't aware of DST rules, so use a consistent non-DST offset when creating a DateTime with an offset in the local zone
+          def local_offset
+            ::Time.local(2007).utc_offset.to_r / 86400
+          end
+        end
 
         # Seconds since midnight: DateTime.now.seconds_since_midnight
         def seconds_since_midnight

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

@@ -35,10 +35,9 @@ module ActiveSupport #:nodoc:
         end
 
         # Attempts to convert self to a Ruby Time object; returns self if out of range of Ruby Time class
-        # If self.offset is 0, then will attempt to cast as a utc time; otherwise will attempt to cast in local time zone
+        # If self has an offset other than 0, self will just be returned unaltered, since there's no clean way to map it to a Time
         def to_time
-          method = if self.offset == 0 then 'utc' else 'local' end
-          ::Time.send(method, year, month, day, hour, min, sec) rescue self
+          self.offset == 0 ? ::Time.utc_time(year, month, day, hour, min, sec) : self
         end        
 
         # To be able to keep Times, Dates and DateTimes interchangeable on conversions

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

@@ -35,7 +35,7 @@ module ActiveSupport #:nodoc:
           def time_with_datetime_fallback(utc_or_local, year, month=1, day=1, hour=0, min=0, sec=0, usec=0)
             ::Time.send(utc_or_local, year, month, day, hour, min, sec, usec)
           rescue
-            offset = if utc_or_local.to_sym == :utc then 0 else ::DateTime.now.offset end
+            offset = utc_or_local.to_sym == :local ? ::DateTime.local_offset : 0
             ::DateTime.civil(year, month, day, hour, min, sec, offset, 0)
           end
 

activesupport/test/core_ext/date_ext_test.rb

@@ -174,9 +174,13 @@ class DateExtCalculationsTest < Test::Unit::TestCase
   
   def test_xmlschema
     with_timezone 'US/Eastern' do
-      assert_match(/^1880-06-28T00:00:00-04:?00$/, Date.new(1880, 6, 28).xmlschema)
+      assert_match(/^1980-02-28T00:00:00-05:?00$/, Date.new(1980, 2, 28).xmlschema)
       assert_match(/^1980-06-28T00:00:00-04:?00$/, Date.new(1980, 6, 28).xmlschema)
-      assert_match(/^2080-06-28T00:00:00-04:?00$/, Date.new(2080, 6, 28).xmlschema)
+      # these tests are only of interest on platforms where older dates #to_time fail over to DateTime
+      if ::DateTime === Date.new(1880, 6, 28).to_time
+        assert_match(/^1880-02-28T00:00:00-05:?00$/, Date.new(1880, 2, 28).xmlschema)
+        assert_match(/^1880-06-28T00:00:00-05:?00$/, Date.new(1880, 6, 28).xmlschema) # DateTimes aren't aware of DST rules
+      end
     end
   end
 

activesupport/test/core_ext/date_time_ext_test.rb

@@ -35,8 +35,9 @@ class DateTimeExtCalculationsTest < Test::Unit::TestCase
   # FIXME: ruby 1.9 compat
   def test_to_time
     assert_equal Time.utc(2005, 2, 21, 10, 11, 12), DateTime.new(2005, 2, 21, 10, 11, 12, 0, 0).to_time
-    assert_equal Time.local(2005, 2, 21, 10, 11, 12), DateTime.new(2005, 2, 21, 10, 11, 12, Rational(-5, 24), 0).to_time
     assert_equal Time.utc_time(2039, 2, 21, 10, 11, 12), DateTime.new(2039, 2, 21, 10, 11, 12, 0, 0).to_time
+    # DateTimes with offsets other than 0 are returned unaltered
+    assert_equal DateTime.new(2005, 2, 21, 10, 11, 12, Rational(-5, 24)), DateTime.new(2005, 2, 21, 10, 11, 12, Rational(-5, 24)).to_time
   end
 
   def test_seconds_since_midnight
@@ -211,4 +212,21 @@ class DateTimeExtCalculationsTest < Test::Unit::TestCase
   def test_acts_like_time
     assert DateTime.new.acts_like_time?
   end
+
+  def test_local_offset
+    with_timezone 'US/Eastern' do
+      assert_equal Rational(-5, 24), DateTime.local_offset
+    end
+    with_timezone 'US/Central' do
+      assert_equal Rational(-6, 24), DateTime.local_offset
+    end
+  end
+
+  protected
+    def with_timezone(new_tz = 'US/Eastern')
+      old_tz, ENV['TZ'] = ENV['TZ'], new_tz
+      yield
+    ensure
+      old_tz ? ENV['TZ'] = old_tz : ENV.delete('TZ')
+    end
 end

activesupport/test/core_ext/time_ext_test.rb

@@ -312,7 +312,9 @@ class TimeExtCalculationsTest < Test::Unit::TestCase
     assert_equal "17:44",                           time.to_s(:time)
     assert_equal "February 21, 2005 17:44",         time.to_s(:long)
     assert_equal "February 21st, 2005 17:44",       time.to_s(:long_ordinal)
-    assert_equal "Mon, 21 Feb 2005 17:44:30 +0000", time.to_s(:rfc822)
+    with_timezone "UTC" do 
+      assert_equal "Mon, 21 Feb 2005 17:44:30 +0000", time.to_s(:rfc822)
+    end
   end
 
   def test_custom_date_format
@@ -387,8 +389,8 @@ class TimeExtCalculationsTest < Test::Unit::TestCase
 
   def test_local_time
     assert_equal Time.local_time(2005, 2, 21, 17, 44, 30), Time.local(2005, 2, 21, 17, 44, 30)
-    assert_equal Time.local_time(2039, 2, 21, 17, 44, 30), DateTime.civil(2039, 2, 21, 17, 44, 30, DateTime.now.offset, 0)
-    assert_equal Time.local_time(1901, 2, 21, 17, 44, 30), DateTime.civil(1901, 2, 21, 17, 44, 30, DateTime.now.offset, 0)
+    assert_equal Time.local_time(2039, 2, 21, 17, 44, 30), DateTime.civil(2039, 2, 21, 17, 44, 30, DateTime.local_offset, 0)
+    assert_equal Time.local_time(1901, 2, 21, 17, 44, 30), DateTime.civil(1901, 2, 21, 17, 44, 30, DateTime.local_offset, 0)
   end
 
   def test_next_month_on_31st