Exercism exercise "point mutations" performance test.

point_mutations_perf_text.exs

if System.get_env("EXERCISM_TEST_EXAMPLES") do
  Code.load_file("example.exs")
else
  Code.load_file("point_mutations.exs")
end

ExUnit.start

defmodule DNATest do
  use ExUnit.Case, async: true

  @nucleotides %{1 => ?A, 2 => ?C, 3 => ?G, 4 => ?T}

  test "hamming distance large length" do
    start = :erlang.now
    {list1, list2} = gen_hamming_dna([], [], 1_000_000)
    finish = :erlang.now
    IO.puts :timer.now_diff(finish, start)
    start = :erlang.now
    IO.puts DNA.hamming_distance(list1, list2)
    finish = :erlang.now
    IO.puts :timer.now_diff(finish, start)
  end

  def gen_hamming_dna(list1, list2, 0), do: {list1, list2}
  def gen_hamming_dna(list1, list2, length) do
  	if rem(length, 10) == 0 do
  		nuc1 = get_nucleotide()
  		nuc2 = get_nucleotide()
  		gen_hamming_dna([nuc1|list1], [nuc2|list2], length - 1)
  	else
  		nuc = get_nucleotide()
  		gen_hamming_dna([nuc|list1], [nuc|list2], length - 1)
  	end
  end

  def get_nucleotide() do
  	@nucleotides[:random.uniform(4)]
  end
end