If you have the money to spare (or your employer has a budget for this) I would recommend checking out Kent C Dodds' testingjavascript.com for a full course on testing React applications.
The general idea is that while unit tests can be useful to nail down specifics, most of the time you want what would traditionally be considered integration or even end-to-end tests. Kent is the author of react-testing-library which the course also covers and makes it very easy to do high level testing of React apps.
As a free resource on react-testing-library it might be worth looking at react-testing-examples.com.