How to run rake thinking_sphinx:index in test environment ?

Hi,

I tried 'rake thinking_sphinx:index RAILS_ENV=test'

but it throws following error

F:\test_sarasaves\sarasaves>rake thinking_sphinx:index RAILS_ENV=test
(in F:/test_sarasaves/sarasaves)
Generating Configuration to F:/test_sarasaves/sarasaves/config/
test.sphinx.conf
Sphinx 0.9.8-release (r1533)
Copyright (c) 2001-2008, Andrew Aksyonoff

using config file 'F:/test_sarasaves/sarasaves/config/
test.sphinx.conf'...
FATAL: no sources found in config file.
rake aborted!
The following command failed:
  indexer --config F:/test_sarasaves/sarasaves/config/test.sphinx.conf
--all