Where is my gem file located so that i can rake test

Googling around, I found that apparently adding to the gem file will fix my problems, but where do i find the gem file? what is the name of the gem file?

"group :test do   # Pretty printed test output   gem 'minitest' ####### add this line ####### end"

Here is what happens when i run rake test, please note that i have already installed minitest (2.7.0)

It is called Gemfile and should be in the top level of the rails project (in the directory with app, config and so on.

Colin

Thank you Colin. Issue resolved.