Exercise 2: FakeQuoteFetcher for a Real, Working Preview — Possible Solution
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struct FakeQuoteFetcher: QuoteFetching {
    func fetchQuote() async throws -> Quote {
        Quote(text: "The only way to do great work is to love what you do.",
              author: "Sample Author")
    }
}

#Preview {
    QuoteHeaderView(quoteFetcher: FakeQuoteFetcher())
}

HOW IT WORKS: FakeQuoteFetcher conforms to the exact same real
QuoteFetching protocol Exercise 1's own QuoteHeaderView depends on -
it's a fully legitimate, real substitute from the type system's own
point of view, even though its fetchQuote() implementation returns a
fixed, hardcoded Quote value instantly rather than performing any real
network request. Because it's still marked async and matches the
protocol's own exact signature, it can be awaited exactly like the
real QuoteService, even though no real suspension or network I/O
actually occurs inside it.

Passing FakeQuoteFetcher() into QuoteHeaderView's own initializer
inside the #Preview block means Xcode's own real preview canvas can
render the view's fully-loaded state (the quote text and author shown
directly, skipping the ProgressView state) immediately and
consistently, every single time the preview refreshes - with zero real
dependency on network availability, server response time, or any
actual internet connection while working inside Xcode.

ANSWER: FakeQuoteFetcher conforms to QuoteFetching and returns a fixed
Quote instantly with no real network call, and passing it into
QuoteHeaderView(quoteFetcher: FakeQuoteFetcher()) inside a #Preview
block correctly gives Xcode's own preview canvas real, immediate,
predictable sample data to render, exactly as the chapter's own
FakeAPIClient example demonstrated for TaskListViewModel.

WHY THIS WORKS AS AN ANSWER
------------------------------
This correctly implements a real fake conforming to the protocol and
uses it inside a #Preview exactly as the chapter's own established
pattern demonstrated, giving a concrete, working example of the real
preview benefit the chapter described.