Don't require rubygems in tests; do fall back if necessary

Rakefile

@@ -9,6 +9,7 @@ task :spec => :test
 
 Rake::TestTask.new(:test) do |t|
   t.test_files = FileList['test/*_test.rb']
+  t.ruby_opts = ['-rubygems'] if defined? Gem
 end
 
 desc 'Run compatibility specs (requires test/spec)'

test/helper.rb

@@ -1,5 +1,13 @@
-require 'rubygems' # required so that sinatra/base can require rack
-$:.unshift File.dirname(File.dirname(__FILE__)) + '/lib'
+begin
+  require 'rack'
+rescue LoadError
+  require 'rubygems'
+  require 'rack'
+end
+
+libdir = File.dirname(File.dirname(__FILE__)) + '/lib'
+$LOAD_PATH.unshift libdir unless $LOAD_PATH.include?(libdir)
+
 require 'sinatra/base'
 require 'sinatra/test/unit'