From: Matthew Moss <matthew.moss@...>
Date: 2008-04-20T07:49:49+09:00
Subject: Re: Triangle Area (#160)

Some unit testing for y'all:


require "test/unit"

TOL = 0.0001

class Triangle
  def Triangle.[](*args)
    Triangle.new(*args)
  end
end

class TestTriArea < Test::Unit::TestCase

  def test_3pt_degen
    a = RANDOM_PT.call
    t = Triangle[a, a, a]
    assert_equal(0, t.area)
  end

  def test_2pt_degen
    a, b = RANDOM_PT.call, RANDOM_PT.call
    t = Triangle[a, b, b]
    assert_equal(0, t.area)
  end

  def test_easy
    t = Triangle[Vector[0, 0], Vector[3, 0], Vector[0, 1]]
    assert_in_delta(1.5, t.area, TOL)
  end

  def test_mostly_easy
    t = Triangle[Vector[-11, 0], Vector[5, 0], Vector[0, 3]]
    assert_in_delta(24, t.area, TOL)
  end

  SAMPLES = {
    Triangle[Vector[-42,   4], Vector[-26, -34], Vector[  2,   8]] =>
868.0,
    Triangle[Vector[ 45, -44], Vector[  1,  43], Vector[ 42,  48]] =>
1893.5,
    Triangle[Vector[-24,  29], Vector[ 42,  -1], Vector[ 10,  43]] =>
972.0,
    Triangle[Vector[ 48, -19], Vector[-19,  37], Vector[-15,  36]] =>
78.5,
    Triangle[Vector[-10, -40], Vector[-35, -19], Vector[  1,  33]] =>
1028.0,
    Triangle[Vector[ 28,  23], Vector[-46,  31], Vector[-39,   5]] =>
934.0,
    Triangle[Vector[-32,  17], Vector[-50,  -8], Vector[-39,  27]] =>
177.5,
    Triangle[Vector[ 40, -19], Vector[ 39, -34], Vector[-37, -15]] =>
579.5,
    Triangle[Vector[ 47, -34], Vector[ 26, -37], Vector[ 50,  -7]] =>
279.0,
    Triangle[Vector[-49,  46], Vector[ 29,  46], Vector[  5, -34]] =>
3120.0
  }

  def test_samples
    SAMPLES.each do |t, a|
      assert_in_delta(a, t.area, TOL)
    end
  end
end