added specs for #media_types

spec/unit/request/media_types_spec.rb

@@ -0,0 +1,7 @@
+require 'spec_helper'
+
+describe Zero::Request, '#media_types' do
+  subject { Zero::Request.new(env) }
+  let(:env) { EnvGenerator.get('/foo') }
+  its(:media_types) { should be_an_instance_of(Zero::Request::Accept) }
+end