Improve ActiveSupport::TimeWithZone conversion to YAML

Previously when converting AS::TimeWithZone to YAML it would be output
as a UTC timestamp. Whilst this preserves the time information accurately
it loses the timezone information. This commit changes that so that it is
saved along with the time information. It also provides nicer encoding of
AS::TimeZone instances themselves which previously embedded all of the
data from the TZInfo records.

Fixes rails#9183.

activesupport/CHANGELOG.md

@@ -1,3 +1,9 @@
+*   Encoding ActiveSupport::TimeWithZone to YAML now preserves the timezone information.
+
+    Fixes #9183.
+
+    *Andrew White*
+
 *   Added `ActiveSupport::TimeZone#strptime` to allow parsing times as if
     from a given timezone.
 

activesupport/lib/active_support/time_with_zone.rb

@@ -169,12 +169,13 @@ def as_json(options = nil)
       end
     end
 
-    def encode_with(coder)
-      if coder.respond_to?(:represent_object)
-        coder.represent_object(nil, utc)
-      else
-        coder.represent_scalar(nil, utc.strftime("%Y-%m-%d %H:%M:%S.%9NZ"))
-      end
+    def init_with(coder) #:nodoc:
+      initialize(coder['utc'], coder['zone'], coder['time'])
+    end
+
+    def encode_with(coder) #:nodoc:
+      coder.tag = '!ruby/object:ActiveSupport::TimeWithZone'
+      coder.map = { 'utc' => utc, 'zone' => time_zone, 'time' => time }
     end
 
     # Returns a string of the object's date and time in the format used by

activesupport/lib/active_support/values/time_zone.rb

@@ -428,6 +428,15 @@ def periods_for_local(time) #:nodoc:
       tzinfo.periods_for_local(time)
     end
 
+    def init_with(coder) #:nodoc:
+      initialize(coder['name'])
+    end
+
+    def encode_with(coder) #:nodoc:
+      coder.tag ="!ruby/object:#{self.class}"
+      coder.map = { 'name' => tzinfo.name }
+    end
+
     private
       def parts_to_time(parts, now)
         return if parts.empty?

activesupport/test/core_ext/time_with_zone_test.rb

@@ -1,6 +1,7 @@
 require 'abstract_unit'
 require 'active_support/time'
 require 'time_zone_test_helpers'
+require 'active_support/core_ext/string/strip'
 
 class TimeWithZoneTest < ActiveSupport::TestCase
   include TimeZoneTestHelpers
@@ -123,11 +124,53 @@ def test_xmlschema_with_nil_fractional_seconds
   end
 
   def test_to_yaml
-    assert_match(/^--- 2000-01-01 00:00:00(\.0+)?\s*Z\n/, @twz.to_yaml)
+    yaml = <<-EOF.strip_heredoc
+      --- !ruby/object:ActiveSupport::TimeWithZone
+      utc: 2000-01-01 00:00:00.000000000 Z
+      zone: !ruby/object:ActiveSupport::TimeZone
+        name: America/New_York
+      time: 1999-12-31 19:00:00.000000000 Z
+    EOF
+
+    assert_equal(yaml, @twz.to_yaml)
   end
 
   def test_ruby_to_yaml
-    assert_match(/---\s*\n:twz: 2000-01-01 00:00:00(\.0+)?\s*Z\n/, {:twz => @twz}.to_yaml)
+    yaml = <<-EOF.strip_heredoc
+      ---
+      twz: !ruby/object:ActiveSupport::TimeWithZone
+        utc: 2000-01-01 00:00:00.000000000 Z
+        zone: !ruby/object:ActiveSupport::TimeZone
+          name: America/New_York
+        time: 1999-12-31 19:00:00.000000000 Z
+    EOF
+
+    assert_equal(yaml, { 'twz' => @twz }.to_yaml)
+  end
+
+  def test_yaml_load
+    yaml = <<-EOF.strip_heredoc
+      --- !ruby/object:ActiveSupport::TimeWithZone
+      utc: 2000-01-01 00:00:00.000000000 Z
+      zone: !ruby/object:ActiveSupport::TimeZone
+        name: America/New_York
+      time: 1999-12-31 19:00:00.000000000 Z
+    EOF
+
+    assert_equal(@twz, YAML.load(yaml))
+  end
+
+  def test_ruby_yaml_load
+    yaml = <<-EOF.strip_heredoc
+      ---
+      twz: !ruby/object:ActiveSupport::TimeWithZone
+        utc: 2000-01-01 00:00:00.000000000 Z
+        zone: !ruby/object:ActiveSupport::TimeZone
+          name: America/New_York
+        time: 1999-12-31 19:00:00.000000000 Z
+    EOF
+
+    assert_equal({ 'twz' => @twz }, YAML.load(yaml))
   end
 
   def test_httpdate

activesupport/test/time_zone_test.rb

@@ -487,4 +487,13 @@ def test_us_zones
     assert ActiveSupport::TimeZone.us_zones.include?(ActiveSupport::TimeZone["Hawaii"])
     assert !ActiveSupport::TimeZone.us_zones.include?(ActiveSupport::TimeZone["Kuala Lumpur"])
   end
+
+  def test_to_yaml
+    assert_equal("--- !ruby/object:ActiveSupport::TimeZone\nname: Pacific/Honolulu\n", ActiveSupport::TimeZone["Hawaii"].to_yaml)
+    assert_equal("--- !ruby/object:ActiveSupport::TimeZone\nname: Europe/London\n", ActiveSupport::TimeZone["Europe/London"].to_yaml)
+  end
+
+  def test_yaml_load
+    assert_equal(ActiveSupport::TimeZone["Pacific/Honolulu"], YAML.load("--- !ruby/object:ActiveSupport::TimeZone\nname: Pacific/Honolulu\n"))
+  end
 end