Challenge 2: Choosing the Right Query Prefix — Possible Solution
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(a) Confirming an error message is NOT shown before form submission
    -> queryBy (e.g. queryByText("Invalid email"))
    Because the element is EXPECTED to be absent, queryBy is required
    specifically because it returns null instead of throwing when
    nothing is found. Using getBy here would make the test itself
    throw an error before the assertion even runs — getBy is built on
    the assumption the element SHOULD exist, which is the opposite of
    what's being verified here. The assertion would typically be
    expect(queryByText("Invalid email")).not.toBeInTheDocument().

(b) Confirming a submit button exists immediately after rendering
    -> getBy (e.g. getByRole("button", {name: "Submit"}))
    The button is expected to be present synchronously, right after
    render() runs, with no waiting involved — exactly this chapter's
    definition of when getBy is the right choice, since a missing
    button here represents a genuine, immediate test failure that
    should throw right away with a clear error.

(c) Confirming a "Success!" message appears after an async save
    completes -> findBy (e.g. findByText("Success!"))
    The message doesn't exist yet at the moment render() finishes —
    it only appears later, once an asynchronous operation resolves.
    findBy is specifically built for this: it returns a Promise and
    retries the query for a period of time, succeeding once the
    element eventually appears rather than failing immediately the
    way getBy would if checked too early.