memo
http://www.ark-web.jp/sandbox/wiki/index.php?%CA%D9%B6%AF%B2%F1%2FRails%A4%CB%A4%E8%A4%EB%A5%C6%A5%B9%A5%C8%BA%EE%C0%AE
http://jp.rubyist.net/magazine/?cmd=view&p=0013-RubyOnRails&key=test
http://www.ruby-lang.org/ja/man/?cmd=view;name=Test%3A%3AUnit
http://pub.cozmixng.org/~hiki/programming/?(Test%3A%3AUnit)%A5%C1%A5%E5%A1%BC%A5%C8%A5%EA%A5%A2%A5%EB
http://manuals.rubyonrails.com/read/book/5
http://api.rubyonrails.org/classes/Test/Unit/Assertions.html