Possibly faster spec runs

exp.md

This is an experiment for possible faster boot time (and consequently faster feedback) when running tests. I ask your help to try this in your apps (any Rails 3.x app) and let me know how well it works.

How to

Add the following lines inside the configuration block in config/environments/test.rb:

config.cache_classes = true
def eager_load!; end

Notice that config.cache_classes needs to be true (which is the default), some tools may not be fine that. Needless to say, just do this for test environments.

Tests

The following two benches will work only for rspec running from the command line (hopefully you don't use rake to run your specs):

1. Pick up a spec file that runs all specs under 1s (for example, a file under spec/models or spec/helpers). Run the command below before and after you apply the eager_load! patch above (the bigger your application, the faster it should boot after you apply the patch):

   time rspec spec/models/SOME_MODEL_spec.rb

2. Try running your whole suite with and without the patch. In this case, you shouldn't see any perf difference and everything should work just fine (report if it doesn't!).

Let me know how 1) and 2) goes in the comments section below.

Entire suite

Baseline

Finished in 4 minutes 3.04 seconds
2699 examples, 0 failures, 3 pending

real  4m10.776s
user  4m2.966s
sys 0m6.156s

Patched

Finished in 4 minutes 3.63 seconds
2699 examples, 0 failures, 3 pending

real  4m10.949s
user  4m3.393s
sys 0m5.989s

Single spec file - 3 runs with each

Baseline

12 examples, 0 failures
Finished in 0.20853 seconds
Finished in 0.20797 seconds
Finished in 0.20495 seconds

real  0m4.882s 0m4.921s 0m4.914s
user  0m4.374s 0m4.365s 0m4.362s
sys   0m0.664s 0m0.705s 0m0.704s

Patched

12 examples, 0 failures
Finished in 0.26532 seconds
Finished in 0.27075 seconds
Finished in 0.26828 seconds

real  0m3.816s 0m3.749s 0m3.760s
user  0m3.428s 0m3.435s 0m3.440s
sys 0m0.528s 0m0.480s 0m0.484s