Error in timezone offset calculation

vim-rails-migration-edit.rb

require 'date'
require 'minitest/autorun'

class TestMeme < MiniTest::Unit::TestCase

  def time_to_timestamp(now:)
    hours_in_seconds = now.strftime('%H').to_i * 3600
    minutes_in_seconds = now.strftime('%M').to_i * 60
    seconds = now.strftime('%S').to_i

    local_now = hours_in_seconds + minutes_in_seconds + seconds

    offset_now = local_now - now.to_i % (24 * 3600)
    if offset_now <= -12 * 60 * 60
      offset_now += (24 * 3600)
    # elsif offset_now >= 12 * 60 * 60
    #   offset_now -= (24 * 3600)
    end

    Time.at(now.to_i - offset_now).to_datetime.strftime('%Y%m%d%H%M%S')
  end

  # passes
  def test_630pm_central
    time = Time.new(2016, 04, 01, 18, 30, 0, "-05:00")
    assert_equal time_to_timestamp(now: time), '20160401233000'
  end

  # fails without lines 16 and 17
  def test_730pm_central
    time = Time.new(2016, 04, 01, 19, 30, 0, "-05:00")
    assert_equal time_to_timestamp(now: time), '20160402003000'
  end
end