oyster_card:伦敦牡蛎卡旅行支付系统的模拟

牡蛎卡挑战赛 本周的挑战将从回顾上周我们在Boris Bikes中介绍的基础知识开始，使您有机会强化上周学到的知识。 然后，您将面临构建一个更加复杂的系统的挑战，该系统应该真正扩展您在Ruby，TDD和面向对象设计中的技能。 每周挑战用户故事 以下是您将为此项目工作的用户故事： In order to use public transport As a customer I want money on my card In order to keep using public transport As a customer I want to add money to my card In order to protect my money As a customer I don't want to put too much money on my card In order to pa