rspec-profiler

Currently tested _with rspec-2.8.0 and above

The rspec-profiler is a custom formatter that adds functionality to the existing —profile option in
rspec. The rspec-profiler first groups tests together by their folder under the spec directory
(models, lib, controllers, etc…). Then the standard deviation is calculated. Any test within a
group that is 2 or more standard deviations away from the mean is listed.

There are downsides of course to doing it this way. For example, with a mean of .02 seconds and a
standard deviation of .01 seconds, a test that takes .04 seconds will be listed when perhaps one
wouldn’t think a test that takes 0.04 seconds to complete to be in need of attention. I will simply
advise, as with any benchmark, to not take the results too seriously. Rather, you should use the
results as a way to identify tests that may need to be looked at for performance issues. And, as
always, running the benchmark multiple times will give you a better sense of the tests that are
consistantly slow. A test may be benchmarked noticably slower in one trial due any number of reasons
but run faster in the next.

1. Put the profiler in your Gemfile

2. When running your specs use:

$ rspec --format Profiler -p spec

If for some reason rspec cannot find the Profiler, you case use the -r option and provide the PATH
to profiler.rb.

Alternatively, you can make the Profiler formatter your default formatter by modifying your .rspec
file (the Profiler inherits from the Progress formatter, you know, the one that uses the green dots):

--format Profiler

Note: The performance profile will not display unless you specify the -p option when running
rspec. Additionally, when tests fail, the profile will not display which is consistant with how the
bundled profiler works as well.

If you use Timecop: If you use the timecop gem to freeze or change time be sure to also return the
time after each of your tests. Not doing so will make it appear as if your tests are taking either
far too long or have taken negative time to complete.