I built this testing tool at a previous employer: https://github.com/smaato/react-test-kit. It's very very simple, it just exposes jQuery-like methods for querying the DOM (and internally uses Sizzle).

Here's an example of how we used react-test-kit to test a SearchBox component: https://github.com/smaato/ui-framework/blob/develop/src/fram...

Here's the interactive component example: http://smaato.github.io/ui-framework/#/searchbox