exclusive_between.rb

require 'minitest/autorun'

module ExclusiveRange
  refine Range do
    def rinclude? value
      self.begin < value && value <= self.end
    end
  end
end

using ExclusiveRange

def exclusive_between? min, max, value
  (min..max).rinclude? value
end

class TestExclusiveBetween < Minitest::Test
  def assert_between min, max, value
    is_between = exclusive_between? min, max, value
    assert is_between, "expected #{value} to be > #{min} and <= #{max}"
  end

  def refute_between min, max, value
    is_between = exclusive_between? min, max, value
    refute is_between, "expected #{value} to not be > #{min} and <= #{max}"
  end

  def test_number_between_min_and_max
    assert_between 0.0, 1.0, 0.4
  end

  def test_maximum_is_included
    assert_between 0.0, 1.0, 1.0
  end

  def test_just_a_little_above_minimum_is_included
    assert_between 0.0, 1.0, Float::EPSILON
  end

  def test_minimum_is_excluded
    refute_between 0.0, 1.0, 0.0
  end

  def test_above_max_is_excluded
    refute_between 0.0, 1.0, 2.0
  end

  def test_just_a_little_above_maximum_is_excluded
    refute_between 0.0, 1.0, 1.0+Float::EPSILON
  end
end