cycle_tracks.rb

def skip_tracks(playlist, skip)
  if skip > 0
    skip.times { playlist.push playlist.shift }
  else
    skip.abs.times { playlist.unshift playlist.pop }
  end
  playlist
end

skipping.feature

Feature: Track skipping

  In order to ignore some tracks

  I want to be able to skip them


  Scenario Outline: Skipping forward
    Given the playlist "a, b, c, d"
    When I skip <skip> track forward
    Then I should have the playlist "<result>"
    Examples:
      | skip |   result  |
      |   1  |  b,c,d,a  |
      |   2  |  c,d,a,b  |
      |   3  |  d,a,b,c  |
      |   4  |  a,b,c,d  |
      |   5  |  b,c,d,a  |
      |   6  |  c,d,a,b  |
      
  Scenario Outline: Skipping backward
    Given the playlist "a, b, c, d"
    When I skip <skip> track backward
    Then I should have the playlist "<result>"
    Examples:
      | skip |   result  |
      |   1  |  d,a,b,c  |
      |   2  |  c,d,a,b  |
      |   3  |  b,c,d,a  |
      |   4  |  a,b,c,d  |
      |   5  |  d,a,b,c  |
      |   6  |  c,d,a,b  |

skipping_steps.rb

Given /^the playlist "([^"]*)"$/ do |list|
  @playlist = list.split(',').map { |x| x.strip }
end

When /^I skip (\d+) tracks? (\w+)$/ do |count, direction|
  skip_count = count.to_i * (direction == 'forward' ? 1 : -1)
  @playlist = skip_tracks(@playlist, skip_count)
end

Then /^I should have the playlist "([^"]*)"$/ do |list|
  @playlist.should == list.split(',').map { |x| x.strip }
end