You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: test_date_arith.rb
    path of file: ./repos/ruby-packer/ruby/test/date
    
    the code of the file until where you have to start completion: # frozen_string_literal: true
require 'test/unit'
require 'date'

class TestDateArith < Test::Unit::TestCa
    
  def test_next
    d = Date.new(2000,12,31).next
    assert_equal([2001, 1, 1], [d.year, d.mon, d.mday])
    d = Date.new(2000,12,31).succ
    assert_equal([2001, 1, 1], [d.year, d.mon, d.mday])

    d = Date.today
    d2 = d.next
    assert_equal(d, (d2 - 1))
    d = Date.today
    d2 = d.succ
    assert_equal(d, (d2 - 1))

    d = DateTime.now
    d2 = d.next
    assert_equal(d, (d2 - 1))
    d = DateTime.now
    d2 = d.succ
    assert_equal(d, (d2 - 1))
  end