Fix jekyll serve --limit_posts n failed

test/test_generated_site.rb

@@ -68,5 +68,15 @@ class TestGeneratedSite < Test::Unit::TestCase
         @site = Site.new(Jekyll.configuration)
       end
     end
+
+    should "ensure if limit_posts is a String (from CLI option)" do
+      clear_dest
+      stub(Jekyll).configuration do
+        Jekyll::Configuration::DEFAULTS.merge({'limit_posts' => "3"})
+      end
+      @site = Site.new(Jekyll.configuration)
+
+      assert_equal 3, @site.limit_posts
+    end
   end
 end