Testing async and the network

await works right inside a @Test

Module 13 covered async/await for concurrency; testing it is almost anticlimactic — mark the test function async and await the call under test, same as anywhere else:

@Test func fetchWalkersReturnsResults() async throws {
    let client: APIClient = LiveAPIClient()
    let walkers = try await client.fetchWalkers()
    #expect(!walkers.isEmpty)
}

But that test as written has a problem: it hits the real network, through the real LiveAPIClient. Now the test is slow, can fail because a server is down (not because your code is wrong), and needs internet access to run at all in CI.