ruby - Need help with require while modifiying a gem (active_merchant) -

i'm trying add new gateway active_merchant gem , i'm having 'require' issues when try run source.

(i think problem not active_merchant-specific, more of general ruby environment issue, dont think specific gem in use has it.)

this i've done:

1. cloned git repo am, local directory "c:\users\jb\documents\aptana studio 3 workspace\active_merchant"

2. went doing changes in "billing/gateways" directory (this background info..)

3. copied "sample usage" example on am's git repo c:\users\jb\documents\aptana studio 3 workspace\simple_gw_test.rb, starts with:
   require 'rubygems'
require 'active_merchant'

4. ran "ruby simple_gw_test.rb" , got error message:

   <internal:lib/rubygems/custom_require>:29:in `require': no such file load -- active_merchant (loaderror) <internal:lib/rubygems/custom_require>:29:in 'require' simple_gw_test.rb:3:in '<main>'


this understandable, since don't have active_merchant gem installed

however, want use downloaded source in sample file, since i'm modifying gateway source continually.

i tried
require '/users/jb/documents/aptana studio 3 workspace/active_merchant'

and got same error:
<internal:lib/rubygems/custom_require>:29:in require': no such file load -- /users/jb/documents/aptana studio 3 workspace/active_merchant (loaderror) &lt;internal:lib/rubygems/custom_require&gt;:29:inrequire' simple_gw_test.rb:2:in `<main>';

any ruby guru can shed light appreaciated!

--jb

ps: i'm using mri 1.9.2 on windows 7 x64.

make sure have read access file. ruby has given me error before when didn't have correct permissions.