Wraps text. using Transformation Priority Premise

wrapper.rb

def find_positions_for_split(text, width)
  if space = text[0..width].rindex(" ")
    [space-1, space+1]
  else
    [width-1, width]
  end
end

def wrap(text, width)
  return "" unless text
  return text if text.length <= width
  first, last = find_positions_for_split(text, width)
  "#{text[0..first]}\n#{wrap(text[last..-1], width)}"
end


describe "Word wrap" do

  # test: nil -> constant
  # code: {} -> nil -> contant
  it "wraps nil to empty string" do
    wrap(nil,3).should eql("")
  end

  it "wraps empty string to empty string" do
    wrap("",3).should eql("")
  end

  # code : const -> scalar
  # code unconditional -> conditional
  it "wraps a single word into a single word" do
    wrap("word", 5).should eql "word"
  end

  # code: unconditional -> conditional
  # code: nil -> constant
  # code: constant -> scalar
  it "breaks long words" do
    wrap("longword", 4).should eql "long\nword"
    # code: statement -> function
    wrap("longerword", 6).should eql "longer\nword"
  end

  # code: statement -> recursion
  it "breaks long words multiple times" do
    wrap("verylongword", 4).should eql "very\nlong\nword"
  end

  # code: unconditional -> conditional
  # code: nil -> constant
  it "splits multiple word on space" do
    wrap("word word", 6).should eql "word\nword"
    # code: statement -> function
    wrap("wrap here", 6).should eql "wrap\nhere"
    # code: statement -> recursion
    wrap("word word word", 6).should eql "word\nword\nword"
  end

  # code: statement -> function
  it "splits at the end" do
    wrap("word word word", 9).should eql "word word\nword"
  end
  it "splits in the middle" do
    wrap("word word word word", 9).should eql "word word\nword word"
    wrap("word word word word", 10).should eql "word word\nword word"
  end

end