Custom RuboCop Cops

TestProf comes with the RuboCop cops that help you write more performant tests.

To enable them, add test-prof in your RuboCop configuration:

# .rubocop.yml
plugins:
 - 'test-prof'

Or you can just use it dynamically:

bundle exec rubocop --plugin 'test-prof' --only RSpec/AggregateExamples

NOTE

The plugin system is supported in RuboCop 1.72+. In earlier versions, use require instead of plugins.

To configure cops to your needs:

RSpec/AggregateExamples:
  AddAggregateFailuresMetadata: false

RSpec/AggregateExamples

This cop encourages you to use one of the greatest features of the recent RSpec – aggregating failures within an example.

Instead of writing one example per assertion, you can group independent assertions together, thus running all setup hooks only once. That can dramatically increase your performance (by reducing the total number of examples).

Consider an example:

# bad
it { is_expected.to be_success }
it { is_expected.to have_header("X-TOTAL-PAGES", 10) }
it { is_expected.to have_header("X-NEXT-PAGE", 2) }
its(:status) { is_expected.to eq(200) }

# good
it "returns the second page", :aggregate_failures do
  is_expected.to be_success
  is_expected.to have_header("X-TOTAL-PAGES", 10)
  is_expected.to have_header("X-NEXT-PAGE", 2)
  expect(subject.status).to eq(200)
end

Auto-correction will typically add :aggregate_failures to examples, but if your project enables it globally, or selectively by e.g. deriving metadata from file location, you may opt-out of adding it using AddAggregateFailuresMetadata config option.

This cop supports auto-correct feature, so you can automatically refactor you legacy tests!

NOTE: its examples shown here have been deprecated as of RSpec 3, but users of the rspec-its gem can leverage this cop to cut out that dependency.

NOTE: auto-correction of examples using block matchers, such as change is deliberately not supported.