TimeZone #local and #now correctly enforce DST rules

git-svn-id: http://svn-commit.rubyonrails.org/rails/trunk@9007 5ecf4fe2-1ee6-0310-87b1-e25e094e27de

3 files changed, 83 insertions, 16 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index ebb25b54e6..f72484d36d 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,5 +1,7 @@
 *SVN*
 
+* TimeZone #local and #now correctly enforce DST rules [Geoff Buesing]
+
 * TimeWithZone instances correctly enforce DST rules. Adding TimeZone#period_for_utc [Geoff Buesing]
 
 * test_time_with_datetime_fallback expects DateTime.local_offset instead of DateTime.now.offset [Geoff Buesing]
diff --git a/activesupport/lib/active_support/values/time_zone.rb b/activesupport/lib/active_support/values/time_zone.rb
index ced823f052..a52eee3e7c 100644
--- a/activesupport/lib/active_support/values/time_zone.rb
+++ b/activesupport/lib/active_support/values/time_zone.rb
@@ -174,25 +174,32 @@ class TimeZone
   def to_s
     "(UTC#{formatted_offset}) #{name}"
   end
-  
-  # Method for creating new ActiveSupport::TimeWithZone instance in time zone of self. Example:
-  #
-  #   Time.zone = "Hawaii"                      # => "Hawaii"
-  #   Time.zone.local(2007, 2, 1, 15, 30, 45)   # => Thu, 01 Feb 2007 15:30:45 HST -10:00
-  def local(*args)
-    Time.utc_time(*args).change_time_zone(self)
-  end
 
   begin # the following methods depend on the tzinfo gem
     require_library_or_gem "tzinfo" unless Object.const_defined?(:TZInfo)
     
+    # Method for creating new ActiveSupport::TimeWithZone instance in time zone of +self+. Example:
+    #
+    #   Time.zone = "Hawaii"                      # => "Hawaii"
+    #   Time.zone.local(2007, 2, 1, 15, 30, 45)   # => Thu, 01 Feb 2007 15:30:45 HST -10:00
+    def local(*args)
+      t = Time.utc_time(*args)
+      begin
+        result = local_to_utc(t)
+      rescue TZInfo::PeriodNotFound
+        t += 1.hour
+        retry
+      end
+      result.in_time_zone(self)
+    end
+    
     # Returns an ActiveSupport::TimeWithZone instance representing the current time
     # in the time zone represented by +self+. Example:
     #
     #   Time.zone = 'Hawaii'  # => "Hawaii"
     #   Time.zone.now         # => Wed, 23 Jan 2008 20:24:27 HST -10:00
     def now
-      tzinfo.now.change_time_zone(self)
+      Time.now.utc.in_time_zone(self)
     end
 
     # Return the current date in this time zone.
@@ -233,7 +240,7 @@ class TimeZone
     
   rescue LoadError # Tzinfo gem is not available
     # re-raise LoadError only when a tzinfo-dependent method is called:
-    %w(now today utc_to_local local_to_utc period_for_local tzinfo).each do |method|
+    %w(local now today utc_to_local local_to_utc period_for_utc period_for_local tzinfo).each do |method|
       define_method(method) {|*args| raise LoadError, "TZInfo gem is required for TimeZone##{method}. `gem install tzinfo` and try again."}
     end
   end
diff --git a/activesupport/test/time_zone_test.rb b/activesupport/test/time_zone_test.rb
index 43f60690d9..de06482af6 100644
--- a/activesupport/test/time_zone_test.rb
+++ b/activesupport/test/time_zone_test.rb
@@ -62,11 +62,32 @@ class TimeZoneTest < Test::Unit::TestCase
 
     uses_mocha 'TestTimeZoneNowAndToday' do
       def test_now
-        TZInfo::DataTimezone.any_instance.stubs(:now).returns(Time.utc(2000))
-        zone = TimeZone['Eastern Time (US & Canada)']
-        assert_instance_of ActiveSupport::TimeWithZone, zone.now
-        assert_equal Time.utc(2000), zone.now.time
-        assert_equal zone, zone.now.time_zone
+        with_env_tz 'US/Eastern' do
+          Time.stubs(:now).returns(Time.local(2000))
+          zone = TimeZone['Eastern Time (US & Canada)']
+          assert_instance_of ActiveSupport::TimeWithZone, zone.now
+          assert_equal Time.utc(2000,1,1,5), zone.now.utc
+          assert_equal Time.utc(2000), zone.now.time
+          assert_equal zone, zone.now.time_zone
+        end
+      end
+      
+      def test_now_enforces_spring_dst_rules
+        with_env_tz 'US/Eastern' do
+          Time.stubs(:now).returns(Time.local(2006,4,2,2)) # 2AM springs forward to 3AM
+          zone = TimeZone['Eastern Time (US & Canada)']
+          assert_equal Time.utc(2006,4,2,3), zone.now.time
+          assert_equal true, zone.now.dst?
+        end
+      end
+      
+      def test_now_enforces_fall_dst_rules
+        with_env_tz 'US/Eastern' do
+          Time.stubs(:now).returns(Time.local(2006,10,29,1)) # 1AM is ambiguous; could be DST or non-DST 1AM
+          zone = TimeZone['Eastern Time (US & Canada)']
+          assert_equal Time.utc(2006,10,29,1), zone.now.time # selects DST 1AM
+          assert_equal true, zone.now.dst?
+        end
       end
     
       def test_today
@@ -134,5 +155,42 @@ class TimeZoneTest < Test::Unit::TestCase
     assert_equal Time.utc(2007, 2, 5, 15, 30, 45), time.time
     assert_equal TimeZone["Hawaii"], time.time_zone
   end
-end
+  
+  def test_local_enforces_spring_dst_rules
+    zone = TimeZone['Eastern Time (US & Canada)']
+    twz = zone.local(2006,4,2,1,59,59) # 1 second before DST start
+    assert_equal Time.utc(2006,4,2,1,59,59), twz.time
+    assert_equal Time.utc(2006,4,2,6,59,59), twz.utc
+    assert_equal false, twz.dst?
+    assert_equal 'EST', twz.zone
+    twz2 = zone.local(2006,4,2,2) # 2AM does not exist because at 2AM, time springs forward to 3AM
+    assert_equal Time.utc(2006,4,2,3), twz2.time # twz is created for 3AM
+    assert_equal Time.utc(2006,4,2,7), twz2.utc
+    assert_equal true, twz2.dst?
+    assert_equal 'EDT', twz2.zone
+    twz3 = zone.local(2006,4,2,2,30) # 2:30AM does not exist because at 2AM, time springs forward to 3AM
+    assert_equal Time.utc(2006,4,2,3,30), twz3.time # twz is created for 3:30AM
+    assert_equal Time.utc(2006,4,2,7,30), twz3.utc
+    assert_equal true, twz3.dst?
+    assert_equal 'EDT', twz3.zone
+  end
+  
+  def test_local_enforces_fall_dst_rules
+    # 1AM during fall DST transition is ambiguous, it could be either DST or non-DST 1AM
+    # Mirroring Time.local behavior, this method selects the DST time
+    zone = TimeZone['Eastern Time (US & Canada)']
+    twz = zone.local(2006,10,29,1)
+    assert_equal Time.utc(2006,10,29,1), twz.time
+    assert_equal Time.utc(2006,10,29,5), twz.utc
+    assert_equal true, twz.dst? 
+    assert_equal 'EDT', twz.zone
+  end
 
+  protected
+    def with_env_tz(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