Guessing Game on Elixir based on blog post http://www.elixirdose.com/elixir-guessing-game/

guessing_game.ex

defmodule GuessingGameUI do

  IO.puts "Elixir Guessing Game\n\n\n"
  IO.puts "========================\n"

  random_number = :random.uniform(10)

  user_input = GuessingGame.convert_user_input(IO.gets('Enter your guess: '))
  {status, message} = GuessingGame.check_user_input(user_input)

  if status == :ok do
    {compare_status, compare_message} = GuessingGame.compare_numbers(random_number, user_input)

    if compare_status == :ok do
      IO.inspect "Conglatulations, You're the winner!"
    else
      IO.inspect compare_message
    end

  else
    IO.inspect message
  end


end

guessing_game_lib.ex

defmodule GuessingGame do

  def check_user_input(number) when number <= 10 do
    {:ok, number}
  end

  def check_user_input(number) do
    {:error, "#{number} is not a valid number. Please input number between 1-10"}
  end

  def convert_user_input(input) do
    input |> String.strip |> binary_to_integer
  end

  def compare_numbers(input_number, guess_number) when input_number == guess_number do
    {:ok, "You Have guessed the number and it is #{input_number}"}
  end

  def compare_numbers(input_number, guess_number) when input_number != guess_number do
   {:error, "you have entered #{input_number}, but the correct random number is #{guess_number}"}
  end

end

guessing_game_test.exs

defmodule GuessingGameTest do
  use ExUnit.Case

  test 'Checking valid user input' do
    assert GuessingGame.check_user_input(5) == {:ok, 5}
    assert GuessingGame.check_user_input(9) == {:ok, 9}
    assert GuessingGame.check_user_input(10) == {:ok, 10}
  end

  test 'Invalid user input' do
    # user input bigger than 10
    assert GuessingGame.check_user_input(11) == {:error,
      "11 is not a valid number. Please input number between 1-10"}
    assert GuessingGame.check_user_input(22) == {:error,
      "22 is not a valid number. Please input number between 1-10"}
  end

  test 'Convert user input' do
    assert GuessingGame.convert_user_input("1") == 1
    assert GuessingGame.convert_user_input("4\n") == 4
  end

  test 'Compare equality of random numbers' do
    assert GuessingGame.compare_numbers(5, 5) == {:ok,
      "You Have guessed the number and it is 5"}

    assert GuessingGame.compare_numbers(8, 8) == {:ok,
      "You Have guessed the number and it is 8"}
  end

  test 'Compare when the guess of random number is wrong' do
    assert GuessingGame.compare_numbers(5, 6) == {:error,
      "you have entered 5, but the correct random number is 6"}

    assert GuessingGame.compare_numbers(8, 1) == {:error,
      "you have entered 8, but the correct random number is 1"}
  end

end