在rspec测试中设置系统时间，不更改系统时钟

I'm working on getting a rails 3 application ready to use time zones. My development machine is in EDT and the servers I'm hosting on are in UTC. Is there a way in my rspec tests to change the system time zone ruby is using so that I'm running tests using the same system time zone without having to change the system clock on my computer? I've looked into Delorean and Timecop and they're not what I'm looking for. I'm looking for something likeI'm working on getting a rails 3 application re