gistfile1.js

let testTree = require('react-test-tree');

class Foo extends React.Component {
    render() {
        return (
            <div className="Foo">
                <Bar ref="bar1" />
                <Bar ref="bar2" />
            </div>
        );
    }
}

class Bar extends React.Component {
    render() {
        return (
            <div className="Bar">
                <Baz ref="baz" />
            </div>
        );
    }
}

class Baz extends React.Component {
    render() {
        return <div className="Baz" />;
    }
}

let foo = testTree(<Foo />, {
    stub: {
        bar1: null, // Don't render this component,
        bar2: {
            baz: <div />, // render div instead
        }
    }
});

expect(foo.bar1).to.not.exist;