TestRequestCancellation.swift

func testRequestCancellation() async throws {

    // Used to synchronize unit test with request task.
    let meeting = TaskMeeting()

    // This request just waits for the unit test in its handler.
    let sut = Request(responseHandler: { _ in
        try? await meeting.rendezvous {}
    })

    // Start unstructured Task that sends the request.
    let requestTask = Task { try await sut.send() }

    // Wait for the request task to proceed to the handler.
    try await meeting.rendezvous {
        // Now, during the handler call, cancel the request's task
        requestTask.cancel()
    }

    // Await the request's result
    let result = await requestTask.result

    // Make sure the request was cancelled
    XCTAssert(result.isCancelled, "not cancelled")
}