Ruby library to easily test time-dependent code

 Timecop makes it easy to travel through or freeze time for creating a
 predictable and ultimately testable scenario.
 .
 It is a wrapper class for manipulating the extensions to the Time, Date,
 and DateTime objects. It avoids overloading of functions with optional
 arguments while writing test cases. It is possible to nest multiple
 calls to Timecop.travel and Timecop.freeze, with each block maintaining
 concept of "now". Having no dependencies, it works with regular Ruby projects
 and Ruby on Rails projects.