zurvan/detail/DateInterceptor.js

A library for simulating time in Node.js

'use strict';
var FieldOverrider = require('./utils/FieldOverrider');
var TypeChecks = require('./utils/TypeChecks');

var forwardedCalls = [
  'valueOf',
  'toUTCString',
  'toTimeString',
  'toString',
  'toSource',
  'toLocaleTimeString',
  'toLocaleFormat',
  'toLocaleDateString',
  'toGMTString',
  'toJSON',
  'toISOString',
  'toDateString',
  'setYear',
  'setUTCSeconds',
  'setUTCMonth',
  'setUTCMinutes',
  'setUTCMilliseconds',
  'setUTCHours',
  'setUTCFullYear',
  'setUTCDate',
  'setTime',
  'setSeconds',
  'setMonth',
  'setMinutes',
  'setMilliseconds',
  'setHours',
  'setFullYear',
  'setDate',
  'getYear',
  'getUTCSeconds',
  'getUTCMonth',
  'getUTCMinutes',
  'getUTCMilliseconds',
  'getUTCHours',
  'getUTCFullYear',
  'getUTCDay',
  'getUTCDate',
  'getTimezoneOffset',
  'getTime',
  'getSeconds',
  'getMonth',
  'getMinutes',
  'getMilliseconds',
  'getHours',
  'getFullYear',
  'getDay',
  'getDate'
];

function fakeDate(timeServer) {
  var OriginalDate = global.Date;

  function makeOriginalDateFromArgs(
    yearOrTimeAsStringOrTimestamp,
    month,
    day,
    hour,
    minute,
    second,
    millisecond
  ) {
    if (TypeChecks.isString(yearOrTimeAsStringOrTimestamp)) {
      return new OriginalDate(yearOrTimeAsStringOrTimestamp);
    }

    if (month === undefined) {
      // means: first argument is a timestamp
      return new OriginalDate(yearOrTimeAsStringOrTimestamp);
    }

    return new OriginalDate(
      yearOrTimeAsStringOrTimestamp,
      month,
      day,
      hour,
      minute,
      second,
      millisecond
    );
  }

  // needs to have 7 arguments to be compliant to length of Date constructor
  function FakeDate(a, b, c, d, e, f, g) {
    var argsArray = [].splice.call(arguments, 0);
    var date =
      argsArray.length === 0
        ? new OriginalDate(Date.now())
        : makeOriginalDateFromArgs.apply(undefined, argsArray);

    if (!(this instanceof FakeDate)) {
      return date.toString();
    }

    this._date = date;
  }

  forwardedCalls.forEach(function(property) {
    if (TypeChecks.isFunction(OriginalDate.prototype[property])) {
      FakeDate.prototype[property] = function() {
        var args = [].splice.call(arguments, 0);
        if (this instanceof OriginalDate) {
          return this[property].apply(this, args);
        }

        return this._date[property].apply(this._date, args);
      };
    }
  });

  FakeDate.UTC = Date.UTC;
  FakeDate.parse = Date.parse;
  FakeDate.now = function() {
    return Math.floor(
      timeServer.systemTimeOffset
        .extended(timeServer.currentTime)
        .toMilliseconds()
    );
  };

  return FakeDate;
}

function DateInterceptor(timeServer) {
  this._fakeDateCreator = fakeDate(timeServer);
}

DateInterceptor.prototype.intercept = function() {
  this.dateOverrider = new FieldOverrider(
    global,
    'Date',
    this._fakeDateCreator
  );
};

DateInterceptor.prototype.release = function() {
  var now = new Date();
  this.dateOverrider.restore();
  return now;
};

module.exports = DateInterceptor;