//! The Neural Engine is reported only once its rail is proved live.
//!
//! On macOS 27.0.1 an unprivileged reader's `ANE0` holds through real Neural
//! Engine work: no advance in 25 sample intervals over 3 s of Core ML
//! inference on the ANE, while root `powermetrics` read 0.47 J of ANE energy
//! over the same span. A figure from it would read 0 J for that work. This
//! runs in a process of its own, so the once-per-process proof starts unproved.

#![cfg(target_os = "macos")]

use std::time::Duration;

use jcp_energy::{npu_rail_liveness, npu_rail_liveness_cached, CounterStatus, Fabric, FabricMeter};

#[test]
fn the_neural_engine_is_reported_only_once_its_rail_is_proved_live() {
    let meter = FabricMeter::detect();
    assert_eq!(npu_rail_liveness_cached(), None, "nothing has probed the ANE rail yet");
    let readable = meter.readable();
    assert!(!readable.iter().any(|(f, _)| *f == Fabric::Npu), "an unproved ANE rail was listed readable: {readable:?}");
    let ((), readings) = meter.measure(|| std::thread::sleep(Duration::from_millis(50)));
    assert!(!readings.iter().any(|r| r.fabric == Fabric::Npu), "an unproved ANE rail gave a figure: {readings:?}");

    // A load that never touches the Neural Engine cannot prove its rail live
    // on this host (macOS 27.0.1, unprivileged), whatever the rail does.
    let status = npu_rail_liveness(|| std::thread::sleep(Duration::from_millis(25)));
    eprintln!("npu rail liveness under a load that never touches the ANE: {status:?}; readable {readable:?}");
    assert_ne!(status, CounterStatus::Live, "the ANE rail was proved live by a load that never touched the ANE");
    assert_eq!(npu_rail_liveness_cached(), Some(status), "the proof was not cached");
    assert!(!meter.readable().iter().any(|(f, _)| *f == Fabric::Npu));
}