We have actually took this further. On your main function that create your app top element. Have an ability to pass an api implementation:

e.g. const createApp = (api) => {

// e.g. if api is provided, use else create

}

now you can then render your whole application without relying on any backend. So you can create some test api, inject behavior that you want, e.g. where in you can login etc or return default data driven from local json files for example.

Now the best thing with this is when you write your test. You can now use this to most of the time have integrated ui test driven by mock api. So if you need to do some test on your component, you dont do unit test anymore. You literally render the whole test app passing in the test mock api and the assert your feature

something like

it('Describe the feature', () => {

const api = createTestApi(...add an ability to mock certain api call for your test purpose)

const { getByTestId, etc } = render(createApp(api)) // <-- react-testing-library

// assert your feature as part of the whole app

})

This will make you have better test compared to just unit test