Add :nsec format only for Ruby 1.9

Ruby 1.8 does not support this format in Time, so the format will only
be added to the available date formats on Ruby 1.9. Changelog entry was
changed to explain that as well.

2 files changed, 5 insertions, 0 deletions

diff --git a/activerecord/CHANGELOG.md b/activerecord/CHANGELOG.md
index 50bbf9dd9b..9e65cc0145 100644
--- a/activerecord/CHANGELOG.md
+++ b/activerecord/CHANGELOG.md
@@ -8,6 +8,7 @@
     *Rafael Mendonça França*
 
 *   Add `:nsec` date format. This can be used to improve the precision of cache key.
+    Please note that this format only works with Ruby 1.9, Ruby 1.8 will ignore it completely.
 
     *Jamie Gaskins*
 
diff --git a/activerecord/test/cases/base_test.rb b/activerecord/test/cases/base_test.rb
index 5631ac9ce2..2324704e15 100644
--- a/activerecord/test/cases/base_test.rb
+++ b/activerecord/test/cases/base_test.rb
@@ -2172,11 +2172,15 @@ class BasicsTest < ActiveRecord::TestCase
   end
 
   def test_cache_key_format_for_existing_record_with_updated_at_1
+    return skip "Only in Ruby 1.9" if RUBY_VERSION < '1.9'
+
     dev = CachedDeveloper.first
     assert_equal "cached_developers/#{dev.id}-#{dev.updated_at.utc.to_s(:nsec)}", dev.cache_key
   end
 
   def test_cache_key_changes_when_child_touched
+    return skip "Only in Ruby 1.9" if RUBY_VERSION < '1.9'
+
     old_timestamp_format = Car.cache_timestamp_format
     Car.cache_timestamp_format = :nsec
     car = Car.create