Infinity Test is a continuous testing library and a flexible alternative to Autotest, using the awesome Watchr library with RSpec, Test::Unit, Bacon and with RVM functionality, giving the possibility to test with all Ruby versions that you have in your RVM configuration.
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gem install infinity_test
After LONG YEARS without developing this gem, in 2014 I'm working to release the 2.0.0 soon. Coming soon!! \o/