Reply to https://twitter.com/geeksam/status/740262903182331905

inverse_hook_filtering.rb

RSpec.configure do |config|
  # Either put conditional logic in the hook...
  config.around(:example) do |ex|
    unless ex.metadata[:slow]
      puts "Not tagged slow"
    end

    ex.run
  end

  # ...or auto-tag everything with `slow: false` in a way that
  # individual groups/examples can override:
  config.define_derived_metadata do |meta|
    meta[:slow] = false unless meta.key?(:slow)
  end

  # ...and then filter on `slow: false`:
  config.around(:example, slow: false) do |ex|
    puts "Not tagged slow"
    ex.run
  end
end