Comment 1 for bug 1319101

Btw, ruby-activesupport-3.2 should be made dependent on ruby-test-unit

Without that package installed, 'rails console' in a newly-created Rails project gives :

/usr/lib/ruby/vendor_ruby/active_support/test_case.rb:12:in `<module:ActiveSupport>': uninitialized constant Test (NameError)

After its installation, the message changes into :

/usr/lib/ruby/vendor_ruby/active_support/test_case.rb:12:in `<module:ActiveSupport>': uninitialized constant Test::Unit::TestCase (NameError)

And as described in Debian bug 738747, adding a line :
require 'test/unit'
in the beginning of the file
/usr/lib/ruby/vendor_ruby/active_support/test_case.rb
eliminates the exception and fixes startup of 'rails console'

So, please, I hope you know what to do.