unexpected-react

Plugin for unexpected to allow for testing the full virtual DOM, and against the shallow renderer (replaces unexpected-react-shallow)

!output_demo

See the blog post for an introduction: https://medium.com/@bruderstein/the-missing-piece-to-the-react-testing-puzzle-c51cd30df7a0

Usage

npm install --save-dev unexpected unexpected-react

If you want to assert over the whole virtual DOM, then you need to emulate the DOM (note this library is not designed for use in the browser - it may be possible, but at the very least, you'll need to disable the react-devtools)

If you don't need the virtual DOM, and you're just using the shallow renderer, then the order of the requires is not important, and you obviously don't need the emulateDom.js require.

// First require your DOM emulation file (see below)
require( '../testHelpers/emulateDom');
 
var unexpected = require('unexpected');
 
// then require unexpected-react
var unexpectedReact = require('unexpected-react');
 
// then react
var React = require('react/addons');
 
// define our instance of the `expect` function to use
const expect = unexpected.clone()
    .use(unexpectedReact);
 

The emulateDom file depends on whether you want to use domino, or jsdom

For jsdom:

// emulateDom.js - jsdom variant
 
if (typeof document === 'undefined') {
 
    const jsdom = require('jsdom').jsdom;
    global.document = jsdom('');
    global.window = global.document.defaultView;
 
    for (let key in global.window) {
        if (!global[key]) {
            global[key] = global.window[key];
        }
    }
}

For domino:

// emulateDom.js - domino variant
 
if (typeof document === 'undefined') {
 
    const domino = require('domino');
    global.window = domino.createWindow('');
    global.document = global.window.document;
    global.navigator = { userAgent: 'domino' };
 
    for (let key in global.window) {
        if (!global[key]) {
            global[key] = global.window[key];
        }
    }
}

From that point on, you can require the components you want to test, and write your tests.

Tests

For the shallow renderer, you can assert on the renderer itself (you can also write the same assertion for the result of getRenderOutput())

 
it('renders with content', function () {
 
    var renderer = TestUtils.createRenderer();
 
    renderer.render(<SomeComponent id={125} />);
 
    return expect(renderer, 'to have rendered',
       <div id={125}>
          Some simple content
       </div>
    );
});

If this fails for some reason, you get a nicely formatted error, with the differences highlighted:

shallow_simple

If you've emulated the DOM, you can write a similar test, but using ReactDOM.render() (or TestUtils.renderIntoDocument())

it('renders with content', function () {
 
    var component = TestUtils.renderIntoDocument(<SomeComponent id={125} />);
 
    return expect(component, 'to have rendered',
       <div id={125}>
          Some simple content
       </div>
    );
});

deeprender_simple

Note the major difference between the shallow renderer and the "normal" renderer, is that child components are also rendered. That is easier to see with these example components:

 
var Text = React.createClass({
   render() {
       return <span>{this.props.content}</span>;
   }
});
 
var App = React.createClass({
   render() {
        return (
            <div className="testing-is-fun">
              <Text content="hello" />
              <Text content="world" />
            </div>
        );
   }
});
 

Rendering the App component with the shallow renderer will not render the spans, only the Text component with the props. If you wanted to test for the content of the span elements, you'd need to use TestUtils.renderIntoDocument(...), or ReactDOM.render(...)

Because unexpected-react` by default ignores wrapper elements, and also "extra" children (child nodes that appear in the actual render, but are not in the expected result), it is possible to test both scenarios with the full renderer. To demonstrate, all the following tests will pass:

 
it('renders the Text components with the spans with the full renderer', function () {
 
   var component = TestUtils.renderIntoDocument(<App />);
 
   expect(component, 'to have rendered', 
      <App>
        <div className="testing-is-fun">
          <Text content="hello">
            <span>hello</span>
          </Text>
          <Text content="world">
            <span>world</span>
          </Text>
        </div>
      </App>
   );
});
 
it('renders the Text nodes with the full renderer', function () {
 
   var component = TestUtils.renderIntoDocument(<App />);
 
   expect(component, 'to have rendered', 
      <div className="testing-is-fun">
         <Text content="hello" />
         <Text content="world" />
      </div>
   );
});
 
it('renders the spans with the full renderer', function () {
 
   var component = TestUtils.renderIntoDocument(<App />);
 
   expect(component, 'to have rendered', 
      <div className="testing-is-fun">
         <span>hello</span>
         <span>world</span>
      </div>
   );
});
 

The first test shows the full virtual DOM that gets rendered. The second test skips the <App> "wrapper" component, and leaves out the <span> children of the <Text> components. The third tests skips both the <App> wrapper component, and the <Text> wrapper component.

Cleaning up

When using the normal renderer, unexpected-react makes use of react-render-hook, which utilises the code from the React devtools. As there is no way for react-render-hook to know when a test is completed, it has to keep a reference to every rendered component. Whilst this shouldn't normally be an issue, if you use a test runner that keeps the process alive (such as wallaby.js), it is a good idea to call unexpectedReact.clearAll() in a global beforeEach() or afterEach() block. This clears the cache of rendered nodes.

Roadmap / Plans

Contributing

We welcome pull requests, bug reports, and extra test cases. If you find something that doesn't work as you believe it should, or where the output isn't as good as it could be, raise an issue!

Thanks

Huge thanks to @Munter for unexpected-dom, and along with @dmatteo from Podio for handing over the unexpected-react name.

Unexpected is a great library to work with, and I offer my sincere thanks to @sunesimonsen and @papandreou, who have created an assertion library that makes testing JavaScript a joy.

License

MIT

Fork me on GitHub