rank-king/test/open_skill_test.rb

require "rank_king/open_skill"

include RankKing

class TestRate < Minitest::Test
  def setup
    @os = OpenSkill.new(tau: 0)
    @a1 = @os.rating(mu: 29.182, sigma: 4.782)
    @b1 = @os.rating(mu: 27.174, sigma: 4.922)
    @c1 = @os.rating(mu: 16.672, sigma: 6.217)
    @d1 = @os.rating
    @e1 = @os.rating
    @f1 = @os.rating
    @w1 = @os.rating(mu: 15)
    @x1 = @os.rating(mu: 20)
    @y1 = @os.rating(mu: 25)
    @z1 = @os.rating(mu: 30)
  end

  def test_rate
    a2, b2, c2, d2 = @os.rate([[@a1], [@b1], [@c1], [@d1]]).flatten

    assert_rating a2, OpenSkill::Rating.new(mu: 30.209971908310553, sigma: 4.764898977359521)
    assert_rating b2, OpenSkill::Rating.new(mu: 27.64460833689499, sigma: 4.882789305097372)
    assert_rating c2, OpenSkill::Rating.new(mu: 17.403586731283518, sigma: 6.100723440599442)
    assert_rating d2, OpenSkill::Rating.new(mu: 19.214790707434826, sigma: 7.8542613981643985)
  end

  def test_tau
    # TODO
  end

  private

  def assert_rating(expected, actual)
    assert_in_delta expected.mu, actual.mu, 0.0001, "Expected #{actual} to equal #{expected}"
    assert_in_delta expected.sigma, actual.sigma, 0.0001, "Expected #{actual} to equal #{expected}"
  end
end

class TestRating < Minitest::Test
  def test_initialize_rating
    rating = OpenSkill.new.rating(mu: 12, sigma: 34)
    assert_in_delta 12, rating.mu
    assert_in_delta 34, rating.sigma

    rating = OpenSkill.new.rating(mu: 42)
    assert_in_delta 42, rating.mu
    assert_in_delta 14, rating.sigma

    rating = OpenSkill.new.rating(sigma: 6.283185)
    assert_in_delta 25, rating.mu
    assert_in_delta 6.283185, rating.sigma

    rating = OpenSkill.new.rating(sigma: 0)
    assert_in_delta 25, rating.mu
    assert_in_delta 0, rating.sigma
  end

  def test_ordinal
    assert_in_delta (-1), OpenSkill::Rating.new(mu: 5, sigma: 2).ordinal
  end
end

class TestUtils < Minitest::Test
  def setup
    @os = OpenSkill.new
    @r = @os.rating
  end

  def test_team_ratings
    # TODO
  end

  def test_utils
    team_1 = [@r]
    team_2 = [@r, @r]
    team_ratings = @os.team_ratings([team_1, team_2])

    c = @os.util_c(team_ratings)
    assert_in_delta 15.590239, c

    sum_q = @os.util_sum_q(team_ratings, c)
    [29.67892702634643, 24.70819334370875].zip(sum_q).each do |actual, expected|
      assert_in_delta actual, expected
    end
  end

  def test_utils_5v5
    team = Array.new(5) { @r }
    team_ratings = @os.team_ratings([team, team])

    c = @os.util_c(team_ratings)
    assert_in_delta 27.003, c

    sum_q = @os.util_sum_q(team_ratings, c)
    [204.84, 102.42].zip(sum_q).each do |actual, expected|
      assert_in_delta actual, expected, 0.01
    end
  end

  def test_util_a
    team = [@r]
    team_ratings = @os.team_ratings([team, team, team, team])
      .zip([1, 1, 1, 4])
      .map { _1.with(rank: _2) }

    a = @os.util_a(team_ratings)

    assert_equal [3, 3, 3, 1], a
  end
end

class TestUnwind < Minitest::Test
  def test_unwind
    assert_equal [[], []], OpenSkill.unwind([], [])
    assert_equal [%w[a], [0]], OpenSkill.unwind(%w[a], [0])
    assert_equal [%w[a b], [1, 0]], OpenSkill.unwind(%w[b a], [1, 0])
    assert_equal [%w[b c a], [1, 2, 0]], OpenSkill.unwind(%w[a b c], [2, 0, 1])
    assert_equal [%w[b d c a], [1, 3, 2, 0]], OpenSkill.unwind(%w[a b c d], [3, 0, 2, 1])
  end

  def test_reverse
    src = (?a..?z).to_a.shuffle
    rank = (0..25).to_a.shuffle
    trans, derank = OpenSkill.unwind(src, rank)
    dst, dederank = OpenSkill.unwind(trans, derank)

    assert_equal src, dst
    refute_same rank, dederank
  end
end