Running tests for acts_as_tree plugin

If I checkout the acts_as_tree plugin from git://github.com/rails/acts_as_tree.git and try to run its unit tests, I get a failure:

$ rake (in /u/home/brian/git/acts_as_tree) /usr/local/bin/ruby -Ilib:lib "/usr/local/lib/ruby/gems/1.8/gems/rake-0.8.3/lib/rake/rake_test_loader.rb" "test/acts_as_tree_test.rb" /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.2/lib/active_support/dependencies.rb:276:in `load_missing_constant': uninitialized constant ActiveRecord::Acts (NameError)   from /usr/local/lib/ruby/gems/1.8/gems/activesupport-2.1.2/lib/active_support/dependencies.rb:468:in `const_missing'   from ./test/../init.rb:1 ... etc

However, I can make them run if I make a one-line addition to init.rb:

diff --git a/init.rb b/init.rb index 0901ddb..3e4d07b 100644 --- a/init.rb +++ b/init.rb @@ -1 +1,2 @@ +require 'active_record/acts/tree' ActiveRecord::Base.send :include, ActiveRecord::Acts::Tree

Is there something odd about my environment, or is this an error in the plugin? I have rails 2.1.2 and rake 0.8.3 gems installed, but I'm testing acts_as_tree separately, not within a rails project.

Thanks,

Brian Candler.