Add rcov_spec task


git-svn-id: https://svn.apache.org/repos/asf/incubator/thrift/trunk@668975 13f79535-47bb-0310-9956-ffa450edef68
diff --git a/lib/rb/Rakefile b/lib/rb/Rakefile
index a41b89b..bd68414 100644
--- a/lib/rb/Rakefile
+++ b/lib/rb/Rakefile
@@ -9,6 +9,13 @@
   t.spec_opts = ['--color']
 end
 
+Spec::Rake::SpecTask.new("rcov_spec") do |t|
+  t.spec_files = FileList['spec/**/*_spec.rb']
+  t.spec_opts = ['--color']
+  t.rcov = true
+  t.rcov_opts = ['--exclude', '^spec,/gems/']
+end
+
 task :test do
   fork do
     exec 'make', '-C', File.dirname(__FILE__) + "/../../test/rb"