React 0.14.7: `<option value="">empty</option>` emits empty string on change
http://jsbin.com/pisita/10/edit?html,js,console,output
React 15.0.0-rc.1`<option value="">empty</option>` emits string with value "empty" on change
http://jsbin.com/bemaze/12/edit?html,js,console,output
This is because React 15.0.0-rc.1 cuts off `value=""` from option tag

return (str + '').replace(/([.?*+\^$\[\]\\(){}|-])/g, '\\$1');
    }
    beforeEach(function() {
      var ReactDefaultInjection = require('ReactDefaultInjection');
      ReactDefaultInjection.inject();
      var ReactDOMComponent = require('ReactDOMComponent');
      var ReactReconcileTransaction = require('ReactReconcileTransaction');
      var NodeStub = function(initialProps) {
        this._currentElement = {props: initialProps};
        this._rootNodeID = 'test';
      };
      Object.assign(NodeStub.prototype, ReactDOMComponent.Mixin);
      genMarkup = function(props) {
        var transaction = new ReactReconcileTransaction();
        return (new NodeStub(props))._createOpenTagMarkupAndPutListeners(
          transaction,
          props
        );
      };
      this.addMatchers({
        toHaveAttribute: function(attr, value) {
          var expected = '(?:^|\\s)' + attr + '=[\\\'"]';
          if (typeof value !== 'undefined') {
            expected += quoteRegexp(value) + '[\\\'"]';
          }