| // Copyright (C) 2022 Igalia, S.L. All rights reserved. |
| // This code is governed by the BSD license found in the LICENSE file. |
| |
| /*--- |
| description: > |
| Verify the time zone arithmetic used in TemporalHelpers.oneShiftTimeZone() |
| against known cases in the implementation's time zone database |
| includes: [compareArray.js, temporalHelpers.js] |
| features: [Temporal] |
| ---*/ |
| |
| function checkTimeZoneArithmetic(shiftInstant, shiftNs, realTimeZoneName, shiftWallTime) { |
| // No need to test this on hosts that don't provide an Intl object. It's |
| // sufficient that the logic is tested on at least one host. |
| if (typeof globalThis.Intl === "undefined") |
| return; |
| |
| const tz = TemporalHelpers.oneShiftTimeZone(shiftInstant, shiftNs); |
| const realTz = new Temporal.TimeZone(realTimeZoneName); |
| |
| assert.sameValue( |
| tz.getOffsetNanosecondsFor(shiftInstant), |
| realTz.getOffsetNanosecondsFor(shiftInstant), |
| 'offset at shift instant' |
| ); |
| const minus1 = shiftInstant.subtract({ hours: 1 }); |
| assert.sameValue( |
| tz.getOffsetNanosecondsFor(minus1), |
| realTz.getOffsetNanosecondsFor(minus1), |
| 'offset at 1 hour before shift' |
| ); |
| const plus1 = shiftInstant.add({ hours: 1 }); |
| assert.sameValue( |
| tz.getOffsetNanosecondsFor(plus1), |
| realTz.getOffsetNanosecondsFor(plus1), |
| 'offset at 1 hour after shift' |
| ); |
| |
| assert.compareArray( |
| tz.getPossibleInstantsFor(shiftWallTime).map((i) => i.epochNanoseconds), |
| realTz.getPossibleInstantsFor(shiftWallTime).map((i) => i.epochNanoseconds), |
| 'possible instants for wall time' |
| ); |
| const before1 = shiftWallTime.subtract({ hours: 1 }); |
| assert.compareArray( |
| tz.getPossibleInstantsFor(before1).map((i) => i.epochNanoseconds), |
| realTz.getPossibleInstantsFor(before1).map((i) => i.epochNanoseconds), |
| 'possible instants for 1 hour before wall time' |
| ); |
| const after1 = shiftWallTime.add({ hours: 1 }); |
| assert.compareArray( |
| tz.getPossibleInstantsFor(after1).map((i) => i.epochNanoseconds), |
| realTz.getPossibleInstantsFor(after1).map((i) => i.epochNanoseconds), |
| 'possible instants for 1 hour after wall time' |
| ); |
| } |
| |
| // Check a positive DST shift from +00:00 to +01:00 |
| checkTimeZoneArithmetic( |
| new Temporal.Instant(1616893200000000000n), |
| 3600e9, |
| 'Europe/London', |
| new Temporal.PlainDateTime(2021, 3, 28, 1) |
| ); |
| |
| // Check a negative DST shift from +00:00 to -01:00 |
| checkTimeZoneArithmetic( |
| new Temporal.Instant(1635642000000000000n), |
| -3600e9, |
| 'Atlantic/Azores', |
| new Temporal.PlainDateTime(2021, 10, 31, 1) |
| ); |
| |
| // Check the no-shift case |
| checkTimeZoneArithmetic( |
| new Temporal.Instant(0n), |
| 0, |
| 'UTC', |
| new Temporal.PlainDateTime(1970, 1, 1) |
| ); |