UG_ UG_ - 1 month ago 29
React JSX Question

React Snapshot testing with jest - Failed prop type: Invalid prop `children` of type `string` supplied

I am trying to test a pure react component.

Component



import React, {Component} from 'react';

class App extends Component {
constructor (props){
super(props);
props.init();
}

render() {
return (
<div className="container-wrapper">
{this.props.children}
</div>
);
}
}

App.propTypes = {
init : React.PropTypes.func,
children : React.PropTypes.element,
};
export default App;


Jest Snapshot Test



import React from 'react';
import App from 'app/main/components/App';
import renderer from 'react-test-renderer';

jest.mock('react-dom');
const blank = jest.fn();
describe('App', () => {
it('Renders App', () => {
const component = renderer.create(<App init={blank}> </App>);
const tree = component.toJSON();
expect(tree).toMatchSnapshot();
});
});


When I execute the test I get below error.

console.error node_modules/fbjs/lib/warning.js:36
Warning: Failed prop type: Invalid prop `children` of type `string` supplied to `App`, expected a single ReactElement.
in App


I can understand that is says Props.children is invalid. How can I mock props.children? Or is there some other way test such components

Answer

You can simply pass a child to your component:

it('Renders App', () => {
    const component = renderer.create(
        <App init={blank}>
            Hello App.
        </App>
    );
    const tree = component.toJSON();
    expect(tree).toMatchSnapshot();
});