sort.rb

def sort(elements)
  return elements if elements.size <= 1
  return elements if elements[0] < elements[1]
  [elements[1], elements[0]]
end

describe "sort" do
  example "empty array => empty array" do
    sort([]).should == []
  end

  example "one element array => one element array" do
    sort([1]).should == [1]
  end

  example "two element array => two element array" do
    sort([1,2]).should == [1,2]
    sort([2,1]).should == [1,2]
  end

  example "three element array => three element array" do
    sort([1,2,5]).should == [1,2,5]
    sort([2,1,5]).should == [1,2,5]
  end
end