http://stackoverflow.com/a/28032078/2602869

range_overlap.rb

require 'minitest'
# require 'minitest/reporters'
# Minitest::Reporters.use! [Minitest::Reporters::DefaultReporter.new({color: true})]

class Range
  include Comparable

  def <=>(other)
    self.begin <=> other.begin
  end

  def self.overlap?(*ranges)
    edges = ranges.sort.flat_map { |range| [range.begin, range.end] }
    edges != edges.sort.uniq
  end
end

class TestRangeCompare < Minitest::Test
  PROVIDED_RANGES = [39600..82800, 39600..70200, 70200..80480].shuffle
  OVERLAPPING_RANGES = [2..12, 6..36, 42..96].shuffle
  NON_OVERLAPPING_RANGES = [2..12, 16..36, 42..96].shuffle

  def test_overlap
    assert_equal true, Range.overlap?(*OVERLAPPING_RANGES)
    assert_equal false, Range.overlap?(*NON_OVERLAPPING_RANGES)
    assert_equal true, Range.overlap?(*PROVIDED_RANGES)
  end
end

Minitest.run