Welcome to RoRtechie.com This gem provides very simple integration of BrainTree with Spree. Include the gem into your Gemfile as follows
gem 'spree_braintree', :git => 'git://github.com/rortechie/spree-braintree.git'
To complete the implementation
Register or login with test account https://sandbox.braintreegateway.com/
Now login to spree as admin and navigate to admin > Configuration > Payment Methods > New payment method You should see Spree::Braintree within dropdown for provider.
Select the same, it shall now ask for Merchant Id, Public Key and Private Key. Enter these as per your account from Braintree
Copyright (c) 2011 [Jay @ Rortechie], released under the New BSD License