Merge commit 'mainstream/master'

15 files changed, 231 insertions, 77 deletions

diff --git a/activesupport/CHANGELOG b/activesupport/CHANGELOG
index e8821060f9..6250f33998 100644
--- a/activesupport/CHANGELOG
+++ b/activesupport/CHANGELOG
@@ -1,3 +1,9 @@
+* Hash.from_xml: datetime xml types overflow to Ruby DateTime class when out of range of Time. Adding tests for utc offsets [Geoff Buesing]
+
+* TimeWithZone #+ and #- : ensure overflow to DateTime with Numeric arg [Geoff Buesing]
+
+* Time#to_json: don't convert to utc before encoding. References #175 [Geoff Buesing]
+
 *2.1.0 RC1 (May 11th, 2008)*
 
 * Remove unused JSON::RESERVED_WORDS, JSON.valid_identifier? and JSON.reserved_word? methods. Resolves #164. [Cheah Chu Yeow]
diff --git a/activesupport/lib/active_support/cache.rb b/activesupport/lib/active_support/cache.rb
index b3c9c23d9f..2f1143e610 100644
--- a/activesupport/lib/active_support/cache.rb
+++ b/activesupport/lib/active_support/cache.rb
@@ -87,8 +87,12 @@ module ActiveSupport
 
       def delete_matched(matcher, options = nil)
         log("delete matched", matcher.inspect, options)
-      end       
-      
+      end
+
+      def exist?(key, options = nil)
+        log("exist?", key, options)
+      end
+
       def increment(key, amount = 1)
         log("incrementing", key, amount)
         if num = read(key)
diff --git a/activesupport/lib/active_support/cache/file_store.rb b/activesupport/lib/active_support/cache/file_store.rb
index 16a2509ce2..5b771b1da0 100644
--- a/activesupport/lib/active_support/cache/file_store.rb
+++ b/activesupport/lib/active_support/cache/file_store.rb
@@ -40,13 +40,18 @@ module ActiveSupport
         end
       end
 
+      def exist?(name, options = nil)
+        super
+        File.exist?(real_file_path(name))
+      end
+
       private
         def real_file_path(name)
           '%s/%s.cache' % [@cache_path, name.gsub('?', '.').gsub(':', '.')]
         end
 
         def ensure_cache_path(path)
-          FileUtils.makedirs(path) unless File.exists?(path)
+          FileUtils.makedirs(path) unless File.exist?(path)
         end
 
         def search_dir(dir, &callback)
diff --git a/activesupport/lib/active_support/cache/mem_cache_store.rb b/activesupport/lib/active_support/cache/mem_cache_store.rb
index bfe7e2ccf3..b3769b812f 100644
--- a/activesupport/lib/active_support/cache/mem_cache_store.rb
+++ b/activesupport/lib/active_support/cache/mem_cache_store.rb
@@ -48,7 +48,13 @@ module ActiveSupport
       rescue MemCache::MemCacheError => e
         logger.error("MemCacheError (#{e}): #{e.message}")
         false
-      end              
+      end
+
+      def exist?(key, options = nil)
+        # Doesn't call super, cause exist? in memcache is in fact a read
+        # But who cares? Reading is very fast anyway
+        !read(key, options).nil?
+      end
 
       def increment(key, amount = 1)       
         log("incrementing", key, amount)
diff --git a/activesupport/lib/active_support/cache/memory_store.rb b/activesupport/lib/active_support/cache/memory_store.rb
index 4872e025cd..6f114273e4 100644
--- a/activesupport/lib/active_support/cache/memory_store.rb
+++ b/activesupport/lib/active_support/cache/memory_store.rb
@@ -24,7 +24,12 @@ module ActiveSupport
         super
         @data.delete_if { |k,v| k =~ matcher }
       end
-      
+
+      def exist?(name,options = nil)
+        super
+        @data.has_key?(name)
+      end
+
       def clear
         @data.clear
       end
diff --git a/activesupport/lib/active_support/core_ext/hash/conversions.rb b/activesupport/lib/active_support/core_ext/hash/conversions.rb
index f0f54a92fe..2c606b401b 100644
--- a/activesupport/lib/active_support/core_ext/hash/conversions.rb
+++ b/activesupport/lib/active_support/core_ext/hash/conversions.rb
@@ -70,7 +70,7 @@ module ActiveSupport #:nodoc:
           XML_PARSING = {
             "symbol"       => Proc.new  { |symbol|  symbol.to_sym },
             "date"         => Proc.new  { |date|    ::Date.parse(date) },
-            "datetime"     => Proc.new  { |time|    ::Time.parse(time).utc },
+            "datetime"     => Proc.new  { |time|    ::Time.parse(time).utc rescue ::DateTime.parse(time).utc },
             "integer"      => Proc.new  { |integer| integer.to_i },
             "float"        => Proc.new  { |float|   float.to_f },
             "decimal"      => Proc.new  { |number|  BigDecimal(number) },
diff --git a/activesupport/lib/active_support/core_ext/time/zones.rb b/activesupport/lib/active_support/core_ext/time/zones.rb
index 3ffc71407c..cf28d0fa95 100644
--- a/activesupport/lib/active_support/core_ext/time/zones.rb
+++ b/activesupport/lib/active_support/core_ext/time/zones.rb
@@ -1,9 +1,7 @@
 module ActiveSupport #:nodoc:
   module CoreExtensions #:nodoc:
     module Time #:nodoc:
-      # Methods for creating TimeWithZone objects from Time instances
       module Zones
-        
         def self.included(base) #:nodoc:
           base.extend(ClassMethods) if base == ::Time # i.e., don't include class methods in DateTime
         end
@@ -11,18 +9,31 @@ module ActiveSupport #:nodoc:
         module ClassMethods
           attr_accessor :zone_default
           
+          # Returns the TimeZone for the current request, if this has been set (via Time.zone=). 
+          # If Time.zone has not been set for the current request, returns the TimeZone specified in config.time_zone
           def zone
             Thread.current[:time_zone] || zone_default
           end
 
-          # Sets a global default time zone, separate from the system time zone in ENV['TZ']. 
-          # Accepts either a Rails TimeZone object, a string that identifies a 
-          # Rails TimeZone object (e.g., "Central Time (US & Canada)"), or a TZInfo::Timezone object.
+          # Sets Time.zone to a TimeZone object for the current request/thread. 
+          #
+          # This method accepts any of the following:
+          #
+          #   * a Rails TimeZone object
+          #   * an identifier for a Rails TimeZone object (e.g., "Eastern Time (US & Canada)", -5.hours)
+          #   * a TZInfo::Timezone object
+          #   * an identifier for a TZInfo::Timezone object (e.g., "America/New_York")
+          #
+          # Here's an example of how you might set Time.zone on a per request basis -- current_user.time_zone
+          # just needs to return a string identifying the user's preferred TimeZone:
           #
-          # Any Time or DateTime object can use this default time zone, via <tt>in_time_zone</tt>.
+          #   class ApplicationController < ActionController::Base
+          #     before_filter :set_time_zone
           #
-          #   Time.zone = 'Hawaii'          # => 'Hawaii'
-          #   Time.utc(2000).in_time_zone   # => Fri, 31 Dec 1999 14:00:00 HST -10:00
+          #     def set_time_zone
+          #       Time.zone = current_user.time_zone
+          #     end
+          #   end
           def zone=(time_zone)
             Thread.current[:time_zone] = get_zone(time_zone)
           end
diff --git a/activesupport/lib/active_support/json/encoders/time.rb b/activesupport/lib/active_support/json/encoders/time.rb
index 3660d87c82..57ed3c9e31 100644
--- a/activesupport/lib/active_support/json/encoders/time.rb
+++ b/activesupport/lib/active_support/json/encoders/time.rb
@@ -6,7 +6,7 @@ class Time
   #   # => 2005/02/01 15:15:10 +0000"
   def to_json(options = nil)
     if ActiveSupport.use_standard_json_time_format
-      utc.xmlschema.inspect
+      xmlschema.inspect
     else
       %("#{strftime("%Y/%m/%d %H:%M:%S")} #{formatted_offset(false)}")
     end
diff --git a/activesupport/lib/active_support/testing/setup_and_teardown.rb b/activesupport/lib/active_support/testing/setup_and_teardown.rb
index b2a937edd0..ed8e34510a 100644
--- a/activesupport/lib/active_support/testing/setup_and_teardown.rb
+++ b/activesupport/lib/active_support/testing/setup_and_teardown.rb
@@ -1,6 +1,14 @@
 module ActiveSupport
   module Testing
     module SetupAndTeardown
+      # For compatibility with Ruby < 1.8.6
+      PASSTHROUGH_EXCEPTIONS =
+        if defined?(Test::Unit::TestCase::PASSTHROUGH_EXCEPTIONS)
+          Test::Unit::TestCase::PASSTHROUGH_EXCEPTIONS
+        else
+          [NoMemoryError, SignalException, Interrupt, SystemExit]
+        end
+
       def self.included(base)
         base.send :include, ActiveSupport::Callbacks
         base.define_callbacks :setup, :teardown
@@ -25,7 +33,7 @@ module ActiveSupport
           __send__(@method_name)
         rescue Test::Unit::AssertionFailedError => e
           add_failure(e.message, e.backtrace)
-        rescue *Test::Unit::TestCase::PASSTHROUGH_EXCEPTIONS
+        rescue *PASSTHROUGH_EXCEPTIONS
           raise
         rescue Exception
           add_error($!)
@@ -35,7 +43,7 @@ module ActiveSupport
             run_callbacks :teardown, :enumerator => :reverse_each
           rescue Test::Unit::AssertionFailedError => e
             add_failure(e.message, e.backtrace)
-          rescue *Test::Unit::TestCase::PASSTHROUGH_EXCEPTIONS
+          rescue *PASSTHROUGH_EXCEPTIONS
             raise
           rescue Exception
             add_error($!)
diff --git a/activesupport/lib/active_support/time_with_zone.rb b/activesupport/lib/active_support/time_with_zone.rb
index fbdc680235..c9fb615fa5 100644
--- a/activesupport/lib/active_support/time_with_zone.rb
+++ b/activesupport/lib/active_support/time_with_zone.rb
@@ -1,7 +1,34 @@
 require 'tzinfo'
 module ActiveSupport
   # A Time-like class that can represent a time in any time zone. Necessary because standard Ruby Time instances are 
-  # limited to UTC and the system's ENV['TZ'] zone
+  # limited to UTC and the system's ENV['TZ'] zone.
+  #
+  # You shouldn't ever need to create a TimeWithZone instance directly via .new -- instead, Rails provides the methods
+  # #local, #parse, #at and #now on TimeZone instances, and #in_time_zone on Time and DateTime instances, for a more
+  # user-friendly syntax. Examples:
+  #
+  #   Time.zone = 'Eastern Time (US & Canada)'        # => 'Eastern Time (US & Canada)'
+  #   Time.zone.local(2007, 2, 10, 15, 30, 45)        # => Sat, 10 Feb 2007 15:30:45 EST -05:00
+  #   Time.zone.parse('2007-02-01 15:30:45')          # => Sat, 10 Feb 2007 15:30:45 EST -05:00
+  #   Time.zone.at(1170361845)                        # => Sat, 10 Feb 2007 15:30:45 EST -05:00
+  #   Time.zone.now                                   # => Sun, 18 May 2008 13:07:55 EDT -04:00
+  #   Time.utc(2007, 2, 10, 20, 30, 45).in_time_zone  # => Sat, 10 Feb 2007 15:30:45 EST -05:00
+  #
+  # See TimeZone and ActiveSupport::CoreExtensions::Time::Zones for further documentation for these methods.
+  #
+  # TimeWithZone instances implement the same API as Ruby Time instances, so that Time and TimeWithZone instances are interchangable. Examples:
+  #
+  #   t = Time.zone.now                     # => Sun, 18 May 2008 13:27:25 EDT -04:00
+  #   t.hour                                # => 13
+  #   t.dst?                                # => true
+  #   t.utc_offset                          # => -14400
+  #   t.zone                                # => "EDT"
+  #   t.to_s(:rfc822)                       # => "Sun, 18 May 2008 13:27:25 -0400"
+  #   t + 1.day                             # => Mon, 19 May 2008 13:27:25 EDT -04:00
+  #   t.beginning_of_year                   # => Tue, 01 Jan 2008 00:00:00 EST -05:00
+  #   t > Time.utc(1999)                    # => true
+  #   t.is_a?(Time)                         # => true
+  #   t.is_a?(ActiveSupport::TimeWithZone)  # => true
   class TimeWithZone
     include Comparable
     attr_reader :time_zone
@@ -135,7 +162,7 @@ module ActiveSupport
     # If wrapped #time is a DateTime, use DateTime#since instead of <tt>+</tt>.
     # Otherwise, just pass on to +method_missing+.
     def +(other)
-      result = utc.acts_like?(:date) ? utc.since(other) : utc + other
+      result = utc.acts_like?(:date) ? utc.since(other) : utc + other rescue utc.since(other)
       result.in_time_zone(time_zone)
     end
     
@@ -146,7 +173,7 @@ module ActiveSupport
       if other.acts_like?(:time)
         utc - other
       else
-        result = utc.acts_like?(:date) ? utc.ago(other) : utc - other
+        result = utc.acts_like?(:date) ? utc.ago(other) : utc - other rescue utc.ago(other)
         result.in_time_zone(time_zone)
       end
     end
diff --git a/activesupport/lib/active_support/values/time_zone.rb b/activesupport/lib/active_support/values/time_zone.rb
index 323429d126..886c3e952d 100644
--- a/activesupport/lib/active_support/values/time_zone.rb
+++ b/activesupport/lib/active_support/values/time_zone.rb
@@ -1,3 +1,24 @@
+# The TimeZone class serves as a wrapper around TZInfo::Timezone instances. It allows us to do the following:
+#
+#   * limit the set of zones provided by TZInfo to a meaningful subset of 142 zones
+#   * retrieve and display zones with a friendlier name (e.g., "Eastern Time (US & Canada)" instead of "America/New_York")
+#   * lazily load TZInfo::Timezone instances only when they're needed
+#   * create ActiveSupport::TimeWithZone instances via TimeZone #local, #parse, #at and #now methods
+# 
+# If you set config.time_zone in the Rails Initializer, you can access this TimeZone object via Time.zone:
+#
+#   # environment.rb:
+#   Rails::Initializer.run do |config|
+#     config.time_zone = "Eastern Time (US & Canada)"
+#   end
+#
+#   Time.zone       # => #<TimeZone:0x514834...>
+#   Time.zone.name  # => "Eastern Time (US & Canada)"
+#   Time.zone.now   # => Sun, 18 May 2008 14:30:44 EDT -04:00
+#
+# The version of TZInfo bundled with ActiveSupport only includes the definitions necessary to support the zones 
+# defined by the TimeZone class. If you need to use zones that aren't defined by TimeZone, you'll need to install the TZInfo gem
+# (if a recent version of the gem is installed locally, this will be used instead of the bundled version.)
 class TimeZone
   unless const_defined?(:MAPPING)
     # Keys are Rails TimeZone names, values are TZInfo identifiers
diff --git a/activesupport/lib/active_support/vendor/tzinfo-0.3.8/tzinfo/offset_rationals.rb b/activesupport/lib/active_support/vendor/tzinfo-0.3.8/tzinfo/offset_rationals.rb
index 5857de623d..32fa4123f1 100644
--- a/activesupport/lib/active_support/vendor/tzinfo-0.3.8/tzinfo/offset_rationals.rb
+++ b/activesupport/lib/active_support/vendor/tzinfo-0.3.8/tzinfo/offset_rationals.rb
@@ -27,63 +27,63 @@ module TZInfo
   # -14 and +14 hours to avoid having to call gcd at runtime.  
   module OffsetRationals #:nodoc:
     @@rational_cache = {
-      -50400 => Rational.new!(-7,12), 
-      -48600 => Rational.new!(-9,16),
-      -46800 => Rational.new!(-13,24),
-      -45000 => Rational.new!(-25,48),
-      -43200 => Rational.new!(-1,2),
-      -41400 => Rational.new!(-23,48),
-      -39600 => Rational.new!(-11,24),
-      -37800 => Rational.new!(-7,16),
-      -36000 => Rational.new!(-5,12),
-      -34200 => Rational.new!(-19,48),
-      -32400 => Rational.new!(-3,8),
-      -30600 => Rational.new!(-17,48),
-      -28800 => Rational.new!(-1,3),
-      -27000 => Rational.new!(-5,16),
-      -25200 => Rational.new!(-7,24),
-      -23400 => Rational.new!(-13,48),
-      -21600 => Rational.new!(-1,4),
-      -19800 => Rational.new!(-11,48),
-      -18000 => Rational.new!(-5,24),
-      -16200 => Rational.new!(-3,16),
-      -14400 => Rational.new!(-1,6),
-      -12600 => Rational.new!(-7,48),
-      -10800 => Rational.new!(-1,8),
-       -9000 => Rational.new!(-5,48),
-       -7200 => Rational.new!(-1,12),
-       -5400 => Rational.new!(-1,16),
-       -3600 => Rational.new!(-1,24),
-       -1800 => Rational.new!(-1,48),
-           0 => Rational.new!(0,1),
-        1800 => Rational.new!(1,48),
-        3600 => Rational.new!(1,24),
-        5400 => Rational.new!(1,16),
-        7200 => Rational.new!(1,12),
-        9000 => Rational.new!(5,48),
-       10800 => Rational.new!(1,8),
-       12600 => Rational.new!(7,48),
-       14400 => Rational.new!(1,6),
-       16200 => Rational.new!(3,16),
-       18000 => Rational.new!(5,24),
-       19800 => Rational.new!(11,48),
-       21600 => Rational.new!(1,4),
-       23400 => Rational.new!(13,48),
-       25200 => Rational.new!(7,24),
-       27000 => Rational.new!(5,16),
-       28800 => Rational.new!(1,3),
-       30600 => Rational.new!(17,48),
-       32400 => Rational.new!(3,8),
-       34200 => Rational.new!(19,48),
-       36000 => Rational.new!(5,12),
-       37800 => Rational.new!(7,16),
-       39600 => Rational.new!(11,24),
-       41400 => Rational.new!(23,48),
-       43200 => Rational.new!(1,2),
-       45000 => Rational.new!(25,48),
-       46800 => Rational.new!(13,24),  
-       48600 => Rational.new!(9,16),            
-       50400 => Rational.new!(7,12)}
+      -50400 => Rational(-7,12),
+      -48600 => Rational(-9,16),
+      -46800 => Rational(-13,24),
+      -45000 => Rational(-25,48),
+      -43200 => Rational(-1,2),
+      -41400 => Rational(-23,48),
+      -39600 => Rational(-11,24),
+      -37800 => Rational(-7,16),
+      -36000 => Rational(-5,12),
+      -34200 => Rational(-19,48),
+      -32400 => Rational(-3,8),
+      -30600 => Rational(-17,48),
+      -28800 => Rational(-1,3),
+      -27000 => Rational(-5,16),
+      -25200 => Rational(-7,24),
+      -23400 => Rational(-13,48),
+      -21600 => Rational(-1,4),
+      -19800 => Rational(-11,48),
+      -18000 => Rational(-5,24),
+      -16200 => Rational(-3,16),
+      -14400 => Rational(-1,6),
+      -12600 => Rational(-7,48),
+      -10800 => Rational(-1,8),
+       -9000 => Rational(-5,48),
+       -7200 => Rational(-1,12),
+       -5400 => Rational(-1,16),
+       -3600 => Rational(-1,24),
+       -1800 => Rational(-1,48),
+           0 => Rational(0,1),
+        1800 => Rational(1,48),
+        3600 => Rational(1,24),
+        5400 => Rational(1,16),
+        7200 => Rational(1,12),
+        9000 => Rational(5,48),
+       10800 => Rational(1,8),
+       12600 => Rational(7,48),
+       14400 => Rational(1,6),
+       16200 => Rational(3,16),
+       18000 => Rational(5,24),
+       19800 => Rational(11,48),
+       21600 => Rational(1,4),
+       23400 => Rational(13,48),
+       25200 => Rational(7,24),
+       27000 => Rational(5,16),
+       28800 => Rational(1,3),
+       30600 => Rational(17,48),
+       32400 => Rational(3,8),
+       34200 => Rational(19,48),
+       36000 => Rational(5,12),
+       37800 => Rational(7,16),
+       39600 => Rational(11,24),
+       41400 => Rational(23,48),
+       43200 => Rational(1,2),
+       45000 => Rational(25,48),
+       46800 => Rational(13,24),
+       48600 => Rational(9,16),
+       50400 => Rational(7,12)}
     
     # Returns a Rational expressing the fraction of a day that offset in 
     # seconds represents (i.e. equivalent to Rational(offset, 86400)). 
diff --git a/activesupport/test/core_ext/hash_ext_test.rb b/activesupport/test/core_ext/hash_ext_test.rb
index 706e218abc..69028a123f 100644
--- a/activesupport/test/core_ext/hash_ext_test.rb
+++ b/activesupport/test/core_ext/hash_ext_test.rb
@@ -733,6 +733,44 @@ class HashToXmlTest < Test::Unit::TestCase
 
     assert_equal hash, Hash.from_xml(hash.to_xml(@xml_options))['person']
   end
+  
+  def test_datetime_xml_type_with_utc_time
+    alert_xml = <<-XML
+      <alert>
+        <alert_at type="datetime">2008-02-10T15:30:45Z</alert_at>
+      </alert>
+    XML
+    alert_at = Hash.from_xml(alert_xml)['alert']['alert_at']
+    assert alert_at.utc?
+    assert_equal Time.utc(2008, 2, 10, 15, 30, 45), alert_at
+  end
+  
+  def test_datetime_xml_type_with_non_utc_time
+    alert_xml = <<-XML
+      <alert>
+        <alert_at type="datetime">2008-02-10T10:30:45-05:00</alert_at>
+      </alert>
+    XML
+    alert_at = Hash.from_xml(alert_xml)['alert']['alert_at']
+    assert alert_at.utc?
+    assert_equal Time.utc(2008, 2, 10, 15, 30, 45), alert_at
+  end
+  
+  def test_datetime_xml_type_with_far_future_date
+    alert_xml = <<-XML
+      <alert>
+        <alert_at type="datetime">2050-02-10T15:30:45Z</alert_at>
+      </alert>
+    XML
+    alert_at = Hash.from_xml(alert_xml)['alert']['alert_at']
+    assert alert_at.utc?
+    assert_equal 2050,  alert_at.year
+    assert_equal 2,     alert_at.month
+    assert_equal 10,    alert_at.day
+    assert_equal 15,    alert_at.hour
+    assert_equal 30,    alert_at.min
+    assert_equal 45,    alert_at.sec
+  end
 end
 
 class QueryTest < Test::Unit::TestCase
diff --git a/activesupport/test/core_ext/time_with_zone_test.rb b/activesupport/test/core_ext/time_with_zone_test.rb
index 70c393dd46..c373bca88d 100644
--- a/activesupport/test/core_ext/time_with_zone_test.rb
+++ b/activesupport/test/core_ext/time_with_zone_test.rb
@@ -170,6 +170,13 @@ class TimeWithZoneTest < Test::Unit::TestCase
       assert_equal DateTime.civil(1999, 12, 31, 19, 0 ,5), (twz + 5).time
     end
   end
+  
+  def test_plus_when_crossing_time_class_limit
+    silence_warnings do # silence warnings raised by tzinfo gem
+      twz = ActiveSupport::TimeWithZone.new(Time.utc(2038, 1, 19), @time_zone)
+      assert_equal [0, 0, 19, 19, 1, 2038], (twz + 86_400).to_a[0,6]
+    end
+  end
     
   def test_plus_with_duration
     silence_warnings do # silence warnings raised by tzinfo gem
diff --git a/activesupport/test/json/encoding_test.rb b/activesupport/test/json/encoding_test.rb
index 7bc8eaf06c..38bb8f3e79 100644
--- a/activesupport/test/json/encoding_test.rb
+++ b/activesupport/test/json/encoding_test.rb
@@ -90,6 +90,15 @@ class TestJSONEncoding < Test::Unit::TestCase
   def test_hash_should_allow_key_filtering_with_except
     assert_equal %({"b": 2}), { 'foo' => 'bar', :b => 2, :c => 3 }.to_json(:except => ['foo', :c])
   end
+  
+  def test_time_to_json_includes_local_offset
+    ActiveSupport.use_standard_json_time_format = true
+    with_env_tz 'US/Eastern' do
+      assert_equal %("2005-02-01T15:15:10-05:00"), Time.local(2005,2,1,15,15,10).to_json
+    end
+  ensure
+    ActiveSupport.use_standard_json_time_format = false
+  end
 
   protected
     def with_kcode(code)
@@ -108,6 +117,13 @@ class TestJSONEncoding < Test::Unit::TestCase
     def object_keys(json_object)
       json_object[1..-2].scan(/([^{}:,\s]+):/).flatten.sort
     end
+    
+    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
 
 uses_mocha 'JsonOptionsTests' do