I run a series of tests on Ruby on Rails against a number of different 
vesions of Ruby:

http://intertwingly.net/projects/dashboard.html

Starting with the following revision, I am getting an error with test/unit:

http://redmine.ruby-lang.org/repositories/revision/1?rev=28200

The full error is shown below:

/home/rubys/.rvm/gems/ruby-1.9.2-r28230/gems/test-unit-2.0.9/lib/test/unit/ui/console/testrunner.rb:331:in 
`<module:Console>': uninitialized constant Test::Unit::UI::Console::Diff 
(NameError)
	from 
/home/rubys/.rvm/gems/ruby-1.9.2-r28230/gems/test-unit-2.0.9/lib/test/unit/ui/console/testrunner.rb:17:in 
`<module:UI>'
	from 
/home/rubys/.rvm/gems/ruby-1.9.2-r28230/gems/test-unit-2.0.9/lib/test/unit/ui/console/testrunner.rb:16:in 
`<module:Unit>'
	from 
/home/rubys/.rvm/gems/ruby-1.9.2-r28230/gems/test-unit-2.0.9/lib/test/unit/ui/console/testrunner.rb:15:in 
`<module:Test>'
	from 
/home/rubys/.rvm/gems/ruby-1.9.2-r28230/gems/test-unit-2.0.9/lib/test/unit/ui/console/testrunner.rb:14:in 
`<top (required)>'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from /home/rubys/git/gorp/lib/gorp/test.rb:155:in `<top (required)>'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from /home/rubys/svn/rails4/Book/util/checkdepot.rb:2:in `<top (required)>'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from <internal:lib/rubygems/custom_require>:29:in `require'
	from /home/rubys/git/gorp/lib/gorp/output.rb:110:in `block in <top 
(required)>'

- Sam Ruby