When using RubyTest in Sublime Text 2 to run my tests I initially received an error:

/bin/sh: rspec: command not found

Further research suggested that due to the use of rvm I needed to cd into the rails project directory and then run

subl .

Once I did that I no longer received an error but I also received no output at all. Using

ctrl + `

I was able to determine a different error regarding UnicodeDecodeError. Turns out it is most likely linked to my used of bash-powerline and a fix was mentioned to the Sublime Core team. In the interim changing the code on line 45 of /Users/metafour/Library/Application Support/Sublime Text 2/Packages/Default/exec.py from

proc_env[k] = os.path.expandvars(v).encode(sys.getfilesystemencoding())

to

proc_env[k] = os.path.expandvars(v.decode(sys.getfilesystemencoding())).encode(sys.getfilesystemencoding())

seems to fix the problem.