In React Testing Library tests, keep assertions outside components, and rely on proper global teardown.
- Teardown/cleanup: Since RTL v9, `cleanup()` is automatic when RTL is configured normally. Only call `cleanup()` manually if your test setup does not provide an `afterEach`.
- Assertion placement: Do not use `expect(...)` inside a React component. Instead, render the value to the DOM (or expose it via an element) and assert after render using RTL queries.
- Snapshot restraint: Prefer explicit assertions on specific text/values. Use snapshots only when they meaningfully reduce effort without obscuring intent.
Example (asserting after render, without component-level `expect`):
```js
function Page() {
const { canFetchMore } = useInfiniteQuery(
'items',
(key, nextId = 0) => fetchItems(nextId),
{ initialData: [/* ... */] }
)
return {String(canFetchMore)}
}
const { getByTestId } = render()
expect(getByTestId('can-fetch-more').textContent).toBe('true')
```