Breadth First Traversal in ruby

bft.rb

#!/usr/bin/env ruby
def bft(root)
  buffer = ""
  curr_level = 1
  root[:level] = curr_level
  q = [root]

  while(q.any?) do
    node = q.shift
    if (node[:level] > curr_level)
      curr_level += 1
      buffer << "\n"
    end
    buffer << node[:value]

    if node[:left]
      node[:left][:level] = node[:level] + 1
      q << node[:left]
    end
    if node[:right]
      node[:right][:level] = node[:level] + 1
      q << node[:right]
    end
  end

  buffer
end

require 'minitest/autorun'

describe 'bft' do
  before do
    @tree = {
      root: {
        value: "2",
        left: {
          value: "3",
          left: {
            value: "1"
          }
        },
        right: {
          value: "4",
          left: {
            value: "2"
          },
          right: {
            value: "5"
          }
        }
      }
    }
  end

  describe "#bft" do
    it "should output the tree in levels" do
      results = bft(@tree[:root])
      results.must_equal("2\n34\n125")
    end
  end
end