How to profile RSpec with perftools and bundler?

Question

I need to profile the test suite that I usually run with bundle exec rspec spec/ and produce the GIF image.

What is the command to run the perftools.rb so that it works correctly with bundler?

Answer 1

I too had to dig around to get this. Here is what I did

1. Put this in spec_helper.rb:

   config.before :suite do
     PerfTools::CpuProfiler.start("/tmp/rspec_profile")
   end
   
   config.after :suite do
     PerfTools::CpuProfiler.stop
   end
   

2. Run your rspec

3. Run pprof to get your numbers

   pprof.rb --text  /tmp/rspec_profile