tests/corelib/date_time_far_away_dates_test.dart

// Copyright (c) 2019, the Dart project authors.  Please see the AUTHORS file
// for details. All rights reserved. Use of this source code is governed by a
// BSD-style license that can be found in the LICENSE file.

import "package:expect/expect.dart";

// Dart test program for DateTime, far away dates.

// TODO(37442): Find far-away dates with milliseconds-since-epoch values that
// are 'web' integers.

bool get supportsMicroseconds =>
    DateTime.fromMicrosecondsSinceEpoch(1).microsecondsSinceEpoch == 1;

void testFarAwayDates() {
  DateTime dt =
      DateTime.fromMillisecondsSinceEpoch(1000000000000001, isUtc: true);
  Expect.equals(33658, dt.year);
  Expect.equals(9, dt.month);
  Expect.equals(27, dt.day);
  Expect.equals(1, dt.hour);
  Expect.equals(46, dt.minute);
  Expect.equals(40, dt.second);
  Expect.equals(1, dt.millisecond);
  Expect.equals(0, dt.microsecond);
  dt = DateTime.fromMillisecondsSinceEpoch(-1000000000000001, isUtc: true);
  Expect.equals(-29719, dt.year);
  Expect.equals(4, dt.month);
  Expect.equals(5, dt.day);
  Expect.equals(22, dt.hour);
  Expect.equals(13, dt.minute);
  Expect.equals(19, dt.second);
  Expect.equals(999, dt.millisecond);
  Expect.equals(0, dt.microsecond);

  // Same with local zone.
  dt = DateTime.fromMillisecondsSinceEpoch(1000000000000001);
  Expect.equals(33658, dt.year);
  Expect.equals(9, dt.month);
  Expect.equals(true, dt.day == 27 || dt.day == 26);
  // Not much we can test for local hour.
  Expect.equals(true, dt.hour >= 0 && dt.hour < 24);
  // Timezones can have offsets down to 15 minute.
  Expect.equals(true, dt.minute % 15 == 46 % 15);
  Expect.equals(40, dt.second);
  Expect.equals(1, dt.millisecond);
  Expect.equals(0, dt.microsecond);
  dt = DateTime.fromMillisecondsSinceEpoch(-1000000000000001);
  Expect.equals(-29719, dt.year);
  Expect.equals(4, dt.month);
  Expect.equals(true, 5 == dt.day || 6 == dt.day);
  // Not much we can test for local hour.
  Expect.equals(true, dt.hour >= 0 && dt.hour < 24);
  // Not much we can test for the minute and second.
  //
  // Historical timezones can have arbitrary offets. For example, "Pacific
  // Standard Time" in the United States is represented by Los Angeles. Prior to
  // the adoption of "Railway Time" in the United States at noon on 18 November
  // 1883, the local time in Los Angeles had an offset of a few minutes from the
  // standard time.
  //
  //     -2717640000001   Nov 18 1883 12:07:01 GMT-0752 (Pacific Standard Time)
  //     -2717640000000   Nov 18 1883 12:00:00 GMT-0800 (Pacific Standard Time)
  Expect.equals(true, 0 <= dt.minute && dt.minute < 60);
  Expect.equals(true, 0 <= dt.second && dt.second < 60);
  Expect.equals(999, dt.millisecond);
  Expect.equals(0, dt.microsecond);

  if (!supportsMicroseconds) return;

  // `1000000000000000128` is a valid web number, allowing this test to be
  // compiled by the web compilers.
  dt = DateTime.fromMicrosecondsSinceEpoch(1000000000000000128, isUtc: true);
  Expect.equals(33658, dt.year);
  Expect.equals(9, dt.month);
  Expect.equals(27, dt.day);
  Expect.equals(1, dt.hour);
  Expect.equals(46, dt.minute);
  Expect.equals(40, dt.second);
  Expect.equals(0, dt.millisecond);
  Expect.equals(128, dt.microsecond);
  dt = DateTime.fromMicrosecondsSinceEpoch(-1000000000000000128, isUtc: true);
  Expect.equals(-29719, dt.year);
  Expect.equals(4, dt.month);
  Expect.equals(5, dt.day);
  Expect.equals(22, dt.hour);
  Expect.equals(13, dt.minute);
  Expect.equals(19, dt.second);
  Expect.equals(999, dt.millisecond);
  Expect.equals(1000 - 128, dt.microsecond);

  // Same with local zone.
  dt = DateTime.fromMicrosecondsSinceEpoch(1000000000000000128);
  Expect.equals(33658, dt.year);
  Expect.equals(9, dt.month);
  Expect.equals(true, dt.day == 27 || dt.day == 26);
  // Not much we can test for local hour.
  Expect.equals(true, dt.hour >= 0 && dt.hour < 24);
  // Timezones can have offsets down to 15 minute.
  Expect.equals(true, dt.minute % 15 == 46 % 15);
  Expect.equals(40, dt.second);
  Expect.equals(0, dt.millisecond);
  Expect.equals(128, dt.microsecond);
  dt = DateTime.fromMicrosecondsSinceEpoch(-1000000000000000128);
  Expect.equals(-29719, dt.year);
  Expect.equals(4, dt.month);
  Expect.equals(true, 5 == dt.day || 6 == dt.day);
  // Not much we can test for local hour.
  Expect.equals(true, dt.hour >= 0 && dt.hour < 24);
  // Not much we can test for the minute and second.
  Expect.equals(true, 0 <= dt.minute && dt.minute < 60);
  Expect.equals(true, 0 <= dt.second && dt.second < 60);
  Expect.equals(999, dt.millisecond);
  Expect.equals(1000 - 128, dt.microsecond);
}

void main() {
  testFarAwayDates();
}