support testing on multiple rubies with rbenv

Rakefile

@@ -7,26 +7,38 @@ require 'rspec/core/rake_task'
 RSpec::Core::RakeTask.new(:spec)
 
 namespace :spec do
+  SPEC_PLATFORMS = ENV.has_key?('SPEC_PLATFORMS') ? 
+        ENV['SPEC_PLATFORMS'].split(/ +/) :
+        %w{1.9.3-p448 2.0.0-p247 1.8.7-p374}
+
   desc "Run on three Rubies"
   task :platforms do
-    current = %x{rvm-prompt v}
-
+    # current = %x[rbenv version | awk '{print $1}']
+    
     fail = false
-    %w{1.8.7 1.9.2}.each do |version|
+    SPEC_PLATFORMS.each do |version|
       puts "Switching to #{version}"
       Bundler.with_clean_env do
-        system %{bash -c 'source ~/.rvm/scripts/rvm && rvm #{version} && bundle exec rake spec'}
+        system %{bash -c 'eval "$(rbenv init -)" && rbenv use #{version} && rbenv rehash && ruby -v && bundle exec rake spec'}
       end
       if $?.exitstatus != 0
         fail = true
         break
       end
     end
 
-    system %{rvm #{current}}
-
     exit (fail ? 1 : 0)
   end
+
+  desc 'Install gems for all tested rubies'
+  task :platform_setup do
+     SPEC_PLATFORMS.each do |version|
+      puts "Setting up platform #{version}"
+      Bundler.with_clean_env do
+        system %{bash -c 'eval "$(rbenv init -)" && rbenv use #{version} && rbenv rehash && gem install bundler && bundle install'}
+      end
+    end   
+  end
 end