rails can't find javascript files, how to set up the environment?

I am trying to deploy on a shared host, hostgator, and they have set
up the application
as mydomain/test2.

They suggested the following in config/environments/development.rb

ActionController::AbstractRequest.relative_url_root = "/test2"

With this the application routing works, but the application cannot
load the javascript files.
It looks for mydomain/test2/javascripts/prototype.js?some numbers

I cannot find the actual url of the javascript file to manually load
the javascript file.

the host suggested ENV['ASSETS_DIR'] = '/test2'
but I can't find any documentation on rails environment variable and
it does not work.

any suggestion?