Create tests around math order of operations for zonedDateTimeFns()

[kolton-musgrove]

describe('math order of operations and options', () => {
    const breakoutUnits = (op: any, zdt: Iso.ZonedDateTime, d: any, options: object) =>
      zdt[op]({ years: d.years }, options)
        [op]({ months: d.months }, options)
        [op]({ weeks: d.weeks }, options)
        [op]({ days: d.days }, options)
        [op](
          {
            hours: d.hours,
            minutes: d.minutes,
            seconds: d.seconds,
            milliseconds: d.milliseconds
          },

          options
        )

    it('order of operations: add / none', () => {
      const zdt = zonedDateTimeFns.from('2020-01-31T00:00-08:00[America/Los_Angeles]')
      const d = durationFns.from({ months: 1, days: 1 })
      const options = undefined
      const result = zonedDateTimeFns.add(zdt, d, options)
      assert.equal(result.toString(), '2020-03-01T00:00:00-08:00[America/Los_Angeles]')
      assert.equal(breakoutUnits('add', zdt, d, options).toString(), result.toString())
    })
    it('order of operations: add / constrain', () => {
      const zdt = zonedDateTimeFns.from('2020-01-31T00:00-08:00[America/Los_Angeles]')
      const d = durationFns.from({ months: 1, days: 1 })
      const options = { overflow: 'constrain' }
      const result = zonedDateTimeFns.add(zdt, d, options)
      assert.equal(result.toString(), '2020-03-01T00:00:00-08:00[America/Los_Angeles]')
      assert.equal(breakoutUnits('add', zdt, d, options).toString(), result.toString())
    })
    it('order of operations: add / reject', () => {
      const zdt = zonedDateTimeFns.from('2020-01-31T00:00-08:00[America/Los_Angeles]')
      const d = durationFns.from({ months: 1, days: 1 })
      const options = { overflow: 'reject' }
      assert.throws(() => zonedDateTimeFns.add(zdt, d, options), RangeError)
    })
    it('order of operations: subtract / none', () => {
      const zdt = zonedDateTimeFns.from('2020-03-31T00:00-07:00[America/Los_Angeles]')
      const d = durationFns.from({ months: 1, days: 1 })
      const options = undefined
      const result = zonedDateTimeFns.subtract(zdt, d, options)
      assert.equal(result.toString(), '2020-02-28T00:00:00-08:00[America/Los_Angeles]')
      assert.equal(breakoutUnits('subtract', zdt, d, options).toString(), result.toString())
    })
    it('order of operations: subtract / constrain', () => {
      const zdt = zonedDateTimeFns.from('2020-03-31T00:00-07:00[America/Los_Angeles]')
      const d = durationFns.from({ months: 1, days: 1 })
      const options = { overflow: 'constrain' }
      const result = zonedDateTimeFns.subtract(zdt, d, options)
      assert.equal(result.toString(), '2020-02-28T00:00:00-08:00[America/Los_Angeles]')
      assert.equal(breakoutUnits('subtract', zdt, d, options).toString(), result.toString())
    })
    it('order of operations: subtract / reject', () => {
      const zdt = zonedDateTimeFns.from('2020-03-31T00:00-07:00[America/Los_Angeles]')
      const d = durationFns.from({ months: 1, days: 1 })
      const options = { overflow: 'reject' }
      assert.throws(() => zonedDateTimeFns.subtract(zdt, d, options), RangeError)
    })
  })

The temporal proposal has tests around the order of operations, but they make use of the fact that the hour, minute, second, etc. fields are directly accessible on their objects which makes it simple to access and test them with different math operators. We should create tests around this.