This post is tracing ReactShallowRender flow. ReactShallowRender is a "shallow" render for unit testing, which returns a "shallow" ReactElement tree. "shallow" means that it renders its ReactElement tree only one level. You can use it like this. import assert from 'assert'; import React from 'react'; import TestUtils from 'react-addons-test-utils'; const Child = ({foo}) => <div>{foo}</div>; const