test262/harness/assertRelativeDateMs.js

// Copyright (C) 2015 the V8 project authors. All rights reserved.
// This code is governed by the BSD license found in the LICENSE file.
/*---
description: |
    Verify that the given date object's Number representation describes the
    correct number of milliseconds since the Unix epoch relative to the local
    time zone (as interpreted at the specified date).
defines: [assertRelativeDateMs]
---*/

/**
 * @param {Date} date
 * @param {Number} expectedMs
 */
function assertRelativeDateMs(date, expectedMs) {
  var actualMs = date.valueOf();
  var localOffset = date.getTimezoneOffset() * 60000;

  if (actualMs - localOffset !== expectedMs) {
    $ERROR(
      'Expected ' + date + ' to be ' + expectedMs +
      ' milliseconds from the Unix epoch'
    );
  }
}