RSpecDissect

Do you know how much time you spend in before hooks? Or in memoization helpers such as let? Usually, the most of the whole test suite time.

RSpecDissect provides this kind of information and also shows you the example groups with the highest setup time. The main purpose of RSpecDissect is to identify these slow groups and refactor them using before_all or let_it_be recipes.

Example output:

[TEST PROF INFO] RSpecDissect report

Total time: 25:14.870
Total setup time: 14:36.482

Top 5 slowest suites setup time:

Webhooks::DispatchTransition (./spec/services/webhooks/dispatch_transition_spec.rb:3) – 00:29.895 of 00:33.706 / 327 (before: 00:25.346, before let: 00:19.389, lazy let: 00:04.543)
  ↳ user – 00:09.323 (327)
  ↳ funnel – 00:06.231 (122)
  ↳ account – 00:04.360 (91)

FunnelsController (./spec/controllers/funnels_controller_spec.rb:3) – 00:22.117 of 00:43.649 / 133 (before: 00:22.117, before let: 00:18.695, lazy let: 00:00.000)
  ↳ user – 00:09.323 (327)
  ↳ funnel – 00:06.231 (122)
...

The setup time includes the time spent in before(:each) hooks and lazy let definitions (except subject—it's often used to define the action under test, and, thus, shouldn't be considered a part of the setup phase).

As you can see, the profiler also provides an information about the most time consuming let definitions.

Instructions

RSpecDissect can only be used with RSpec (which is clear from the name).

To activate RSpecDissect use RD_PROF environment variable:

RD_PROF=1 rspec ...

You can also specify the number of top slow groups through RD_PROF_TOP variable:

RD_PROF=1 RD_PROF_TOP=10 rspec ...

You can also specify the number of top let declarations to print through RD_PROF_LET_TOP=10 env var.

Using with RSpecStamp

RSpecDissect can be used with RSpec Stamp to automatically mark slow examples with custom tags. For example:

RD_PROF=1 RD_PROF_STAMP="slow" rspec ...

After running the command above the slowest example groups would be marked with the :slow tag.