Jest is a testing framework that you'll need to figure out how to use. Follow this tutorial to install and run Jest exactly. For example, your testing folder has to be called tests with two underscores or it won't work and jest won't know what to look for:
__tests__
Link here > jest (https://facebook.github.io/jest/docs/getting-started.html#content)
To test React Facebook use the NPM module: react-test-utils.
You'll need to require this at the top of your file.
var ReactTestUtils = require('react-addons-test-utils')
It lets you change react components in your tests.
test('Player', function(t) {
var player = <Player test='testing' />;
ReactTestUtils.renderIntoDocument(player);
t.plan(1);
t.equal(player.props.test, 'testing', 'test property should exists');
});