React 18 Batching Breaks Tests That Assert Immediately After fireEvent

React 18 automatically batches all state updates, including those inside event handlers and async callbacks, so DOM commits are deferred slightly and tests must wrap assertions in waitFor() to observe the update

React 18 removed synchronous rendering entirely, so components no longer update the DOM until the next full page navigation

The tests are failing because React 18 requires all components to be wrapped in Suspense boundaries

React 18 changed event handler signatures, so fireEvent from React 17-era testing libraries no longer triggers handlers correctly