test_scrubble.rb

require 'test/unit'
require 'test/unit/ui/console/testrunner'

def scrubble(array)
  array.dup.inject([]) do |scrubbled, element|
    scrubbled << array.reject { |e| e == element }
  end
end

class ScrubbleTest < Test::Unit::TestCase
  def setup
    @array = %w[one two three]
    @scrubbled_array = [%w[two three], %w[one three], %w[one two]]
  end

  def test_scrubble
    assert_equal(scrubble(@array), @scrubbled_array)
  end
end

Test::Unit::UI::Console::TestRunner.run(ScrubbleTest)