DateMock.js

var YError = require('yerror');

var _localDateCopy = global.Date;

var DateMock = {
  _mocking: false,
  _pendingQueue: [],
  _assignedQueue: [],
  _pendingIndex: 0,
  start: function(theTimeQueue, options) {
    if(DateMock._mocking) {
      throw new YError('E_ALREADY_MOCKING');
    }
    options = options || {};
    DateMock._pendingQueue = theTimeQueue || [];
    DateMock._assignedQueue = [];
    DateMock._pendingIndex = 0;
    DateMock._mocking = true;
    DateMock._tracing = !!options.trace;
    return (options.global ? global : {}).Date = (function() {
      function MockedDate() {
        if(DateMock._tracing) {
          console.trace();
        }
        var args = [];
        if(arguments.length) {
          args = [].slice.call(arguments, 0);
        } else if('undefined' === typeof DateMock._pendingQueue[DateMock._pendingIndex]) {
          throw new YError('E_QUEUE_END', DateMock._pendingQueue, DateMock._pendingIndex);
        } else {
          this._index = DateMock._pendingIndex;
          args = DateMock._pendingQueue[DateMock._pendingIndex++];
          if(!(args instanceof Array)) {
            args = [args];
          }
        }
        this._assignedIndex = DateMock._assignedQueue.length;
        DateMock._assignedQueue.push((new (_localDateCopy.bind.apply(_localDateCopy, [_localDateCopy].concat(args)))).getTime());
      }
      MockedDate.now = function() {
        return (new MockedDate()).getTime();
      };
      MockedDate.parse = function() {
        return _localDateCopy.parse.apply(_localDateCopy, arguments);
      };
      MockedDate.UTC = function() {
        return _localDateCopy.UTC.apply(_localDateCopy, arguments);
      };
      //MockedDate.prototype = {};
      MockedDate.prototype.constructor = _localDateCopy;
      Object.getOwnPropertyNames(_localDateCopy.prototype).forEach(function(key) {
        MockedDate.prototype[key] = function() {
          var aDate = new _localDateCopy(DateMock._assignedQueue[this._assignedIndex]);
          return (aDate)[key].apply(aDate, arguments);
        };
      });
      return MockedDate;
    })();
  },
  stop: function() {
    if(!DateMock._mocking) {
      throw new YError('E_NOT_MOCKING');
    }
    DateMock.stopAnyway();
    if(DateMock._pendingIndex != DateMock._pendingQueue.length) {
      throw new YError('E_QUEUE_UNCOMPLETED', DateMock._pendingIndex, DateMock._pendingQueue.length);
    }
  },
  stopAnyway: function() {
    global.Date = _localDateCopy;
    DateMock._mocking = false;
  }
};

module.exports = DateMock;