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Cover image for Game draw! Building the code and make the tests pass
Diego Novais
Diego Novais

Posted on Edited on

Game draw! Building the code and make the tests pass

#elixir #algorithms #webdev #tutorial

Now we'll code our module Game following the tests.

# lib/game.ex

defmodule Game do
  @moduledoc """
  Documentation for `Game`.
  """
end
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If we run the tests now:

mix test
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We'll see the tests failures:

  1) test Game.play/2 when the players draw when all players choose scissor (GameTest)
     test/game_test.exs:27
     ** (UndefinedFunctionError) function Game.play/2 is undefined or private
     code: assert {:ok, match} = Game.play(first_player_choice, second_player_choise)
     stacktrace:
       (rock_paper_scissor_elixir 0.1.0) Game.play(3, 3)
       test/game_test.exs:31: (test)


  2) test Game.play/2 when the players draw when all players choose paper (GameTest)
     test/game_test.exs:18
     ** (UndefinedFunctionError) function Game.play/2 is undefined or private
     code: assert {:ok, match} = Game.play(first_player_choice, second_player_choise)
     stacktrace:
       (rock_paper_scissor_elixir 0.1.0) Game.play(2, 2)
       test/game_test.exs:22: (test)


  3) test Game.play/2 when the players draw when all players choose stone (GameTest)
     test/game_test.exs:9
     ** (UndefinedFunctionError) function Game.play/2 is undefined or private
     code: assert {:ok, match} = Game.play(first_player_choice, second_player_choise)
     stacktrace:
       (rock_paper_scissor_elixir 0.1.0) Game.play(1, 1)
       test/game_test.exs:13: (test)



Finished in 0.02 seconds (0.00s async, 0.02s sync)
3 tests, 3 failures
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Let's make those tests pass

Firstly, we must create the function play passing two arguments, first_player_choice and second_player_choice:

defmodule Game do
  @moduledoc """
  Documentation for `Game`.
  """

  def play(first_player_choice, second_player_choice) do
  end
end
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And then let's rerun the tests:

mix test
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 1) test Game.play/2 when the players draw when all players choose stone (GameTest)
     test/game_test.exs:9
     match (=) failed
     code:  assert {:ok, match} = Game.play(first_player_choice, second_player_choise)
     left:  {:ok, match}
     right: nil
     stacktrace:
       test/game_test.exs:13: (test)



  2) test Game.play/2 when the players draw when all players choose scissor (GameTest)
     test/game_test.exs:27
     match (=) failed
     code:  assert {:ok, match} = Game.play(first_player_choice, second_player_choise)
     left:  {:ok, match}
     right: nil
     stacktrace:
       test/game_test.exs:31: (test)



  3) test Game.play/2 when the players draw when all players choose paper (GameTest)
     test/game_test.exs:18
     match (=) failed
     code:  assert {:ok, match} = Game.play(first_player_choice, second_player_choise)
     left:  {:ok, match}
     right: nil
     stacktrace:
       test/game_test.exs:22: (test)



Finished in 0.03 seconds (0.00s async, 0.03s sync)
3 tests, 3 failures
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Now we need to guarantee that the game will draw if the player chooses the same item:

defmodule Game do
  @moduledoc """
  Documentation for `Game`.
  """

  def play(first_player_choice, second_player_choice) do
    result(first_player_choice, second_player_choice)
  end

  defp result(first_player_choice, second_player_choice) do
    cond do
      first_player_choice == second_player_choice -> {:ok, "Draw!"}
    end
  end
end
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And now, if we rerun the tests:

mix test
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Everything passed, and everything was ok.

...

Finished in 0.02 seconds (0.00s async, 0.02s sync)
3 tests, 0 failures

Randomized with seed 352470
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In the next post, we'll build the tests covering the scenario when the first player wins.

Contacts

Email: contato@diegonovais.com.br
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