Setup

Install haml-lint:

bundle install

Run haml-lint against the example file

bundle exec haml-lint

Expected output

$ bundle exec haml-lint

1 file inspected, 0 lints detected

Actual output

$ bundle exec haml-lint
example.html.haml:1 [W] RuboCop: Layout/LineLength: Line is too long. [132/120]

1 file inspected, 1 lint detected