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Updating React component state in Jasmine Test

Tags:

javascript

reactjs

I have a relatively simple React component that renders a list based on its state. Then I have a karma/jasmine test that renders the component, sets its state, and checks that the correct markup is rendered.

The problem I'm running into is that every time I do a setState({}) or forceUpdate() on my component, I'm getting an error: 

TypeError: 'undefined' is not an object (evaluating 'deepestAncestor.firstChild')
        at /home/company/projects/user_interface_kit/bower_components/react/react.js:10314

What's the correct way to test state changes in a React component?

React Code:

    var NotificationCenter = React.createClass({

        getInitialState: function(){
            return {notifications:[]}
        },


        render: function() {            

                countContainerStyle = {
                    display: this.state.notifications.length > 0 ? '' : 'none'
                };


            return (
                <div id="pc-notification-center">
                    <span className="pc-notification-center-bell" >
                        B
                    </span>
                    <span className="pc-notification-count-container" style={countContainerStyle}>
                        <span className="pc-notification-count-circle">&#9679;</span>
                        <span className="pc-notification-count">{this.state.notifications.length}</span>
                    </span>
                </div>);
        }

    });

    return NotificationCenter;
});

Test Code:

it('should set its notification count to the number of notifications it has', function() {
        var notificationCenter = NotificationCenter({}),
            countNode;

        TestUtils.renderIntoDocument(notificationCenter);

        notificationCenter.setState({
            notifications: [1,2]
        });


        countNode = TestUtils.findRenderedDOMComponentWithClass(notificationCenter,'pc-notification-count');


        expect(countNode).toBe(2);
    });

Edit: Full stack Trace

PhantomJS 1.9.7 (Linux) [object Object] [object Object] [object Object] should default its notification count to 0 FAILED
TypeError: 'undefined' is not an object (evaluating 'deepestAncestor.firstChild')
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10314
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10260
    at getNode (/home/company/projects/user_interface_kit/bower_components/react/react.js:9874)
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:4472
    at /home/company/projects/user_interface_kit/.tmp/notification_center/popover.js:28
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:5925
    at /home/company/projects/user_interface_kit/.tmp/notification_center/popover.js:75
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:5925
    at /home/company/projects/user_interface_kit/.tmp/notification_center/popover.js:81
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10461
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:11924
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:13944
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:13877
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:4360
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10055
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:11169
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10105
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:11169
    at /home/company/projects/user_interface_kit/.tmp/notification_center/notification_center.js:50
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:10461
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:11924
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:13944
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:13877
    at /home/company/projects/user_interface_kit/bower_components/react/react.js:4360
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:10483
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:11597
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:10533
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:11597
    at /home/company/projects/user_interface_kit/bower_components/react/react-with-addons.js:12716
    at /home/company/projects/user_interface_kit/test/notification_center/notification_center_test.js:19
    at /home/company/projects/user_interface_kit/node_modules/karma-jasmine/lib/adapter.js:171
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1585
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:841
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1074
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:126
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1117
    at each (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:58)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1118
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:895
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1104
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:754
    at callGetModule (/home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1129)
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1479
    at /home/company/projects/user_interface_kit/node_modules/karma-requirejs/lib/require.js:1606

Here is a small project reproducing the issue https://github.com/treehau5/react_karma_requirejs_bug_reproduction

like image 404
Assaf Weinberg Avatar asked Mar 17 '14 19:03

Assaf Weinberg

People also ask

How do you update state of component React?

To update our state, we use this. setState() and pass in an object. This object will get merged with the current state. When the state has been updated, our component re-renders automatically.

Can we directly update the state in React?

State updates in React are asynchronous; when an update is requested, there is no guarantee that the updates will be made immediately. The updater functions enqueue changes to the component state, but React may delay the changes, updating several components in a single pass.

Can we update state in componentDidMount?

You can call setState() immediately in componentDidMount() and triggers an extra rendering, but this happens before the browser updates the screen, calling render() twice.

How do you update a new state in class component?

We have to set initial state value inside constructor function and set click event handler of the element upon which click, results in changing state. Then pass the function to the click handler and change the state of the component inside the function using setState.

2 Answers

After digging deep into how React and React_with_addons works, it looks like the local React object in the test is different than the instance of React that React_with_addons uses. So if you do this in your test:

react_with_addons.addons.TestUtils.renderIntoDocument(componentInstance);

Then react_with_addon's instance of React registers the componentInstance and primes its nodeCache object. The local React instance remains is untouched. Then, if you try to update the component's state like this:

componentInstance.updateState({key:'newValue'});

The local instance of React is used to try to update the DOM. Because no components have ever been mounted with this instance, the update fails and you get the 'undefined' is not an object (evaluating 'deepestAncestor.firstChild') error.

Interestingly, if you mount ANY component into the local React, then you won't see an error when updating a component's state, even if that component was mounted using react_with_addon's React object.

The best way to avoid this problem for now, if your test needs to run setState, is to simply not use react_with_addon's renderIntoDocument function. Instead, just create your own. Its only two lines:

 function renderIntoDocument(instance) {
        var div = document.createElement('div');
        return React.renderComponent(instance, div);
      };
like image 43
Assaf Weinberg Avatar answered Oct 13 '22 02:10

Assaf Weinberg

I don't know if the previous answer is still true.

With React 0.11.1, this code works fine:

var React = require('react/addons');
var TestUtils = React.addons.TestUtils;

jest.dontMock('public/components/MyThing.jsx');
var MyThing = require('public/components/MyThing.jsx');

describe('MyThing', function() {
  var html;

  describe('#render', function() {
    beforeEach(function(){
      var component = MyThing();
      var componentInstance = TestUtils.renderIntoDocument(component);
      componentInstance.setState({isCool: true});

      html = componentInstance.getDOMNode().textContent;
    });

    it('includes something cool', function(){
      expect(html).toContain('something cool');
    });
  });
});
like image 72
duereg Avatar answered Oct 13 '22 01:10

duereg
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