autopilot/crates/scan_controller/tests/state_machine.rs

//! AZ-682 integration tests — exercise the typed state machine and
//! the frame-rate floor monitor end-to-end through the public
//! `ScanControllerHandle` surface.

use uuid::Uuid;

use scan_controller::{RejectReason, ScanController, ScanState, TransitionOutcome, Trigger};

#[tokio::test]
async fn ac1_boot_state_is_zoomed_out() {
    // Arrange
    let h = ScanController::new().handle();

    // Assert
    assert_eq!(h.state().await, ScanState::ZoomedOut);
}

/// AC-2 — transition catalogue is complete; every (from_state,
/// trigger) → to_state from the spec is covered. Spec-disallowed
/// combinations are rejected with a recorded reason.
#[tokio::test]
async fn ac2_full_transition_catalogue_round_trip() {
    // Arrange
    let h = ScanController::new().handle();
    let roi = Uuid::new_v4();
    let target = Uuid::new_v4();

    // Act + Assert — ZoomedOut → ZoomedIn
    let o = h
        .submit_trigger(Trigger::PoiSelected { roi, now_ns: 100 })
        .await;
    assert!(o.accepted, "PoiSelected must transition");
    assert!(matches!(
        h.state().await,
        ScanState::ZoomedIn { roi: r, hold_started_at_ns: 100 } if r == roi
    ));

    // ZoomedIn → TargetFollow
    let o = h
        .submit_trigger(Trigger::TargetConfirmed {
            target_id: target,
            now_ns: 200,
        })
        .await;
    assert!(o.accepted);
    assert!(matches!(
        h.state().await,
        ScanState::TargetFollow { target_id: t, started_at_ns: 200 } if t == target
    ));

    // TargetFollow → ZoomedOut via TargetLost
    let o = h.submit_trigger(Trigger::TargetLost).await;
    assert!(o.accepted);
    assert_eq!(h.state().await, ScanState::ZoomedOut);

    // ZoomedOut → ZoomedIn again → ZoomedOut via RoiRejected
    let _ = h
        .submit_trigger(Trigger::PoiSelected {
            roi: Uuid::new_v4(),
            now_ns: 300,
        })
        .await;
    let o = h.submit_trigger(Trigger::RoiRejected).await;
    assert!(o.accepted);
    assert_eq!(h.state().await, ScanState::ZoomedOut);

    // ZoomedOut → ZoomedIn → ZoomedOut via RoiHoldTimeout
    let _ = h
        .submit_trigger(Trigger::PoiSelected {
            roi: Uuid::new_v4(),
            now_ns: 400,
        })
        .await;
    let o = h.submit_trigger(Trigger::RoiHoldTimeout).await;
    assert!(o.accepted);
    assert_eq!(h.state().await, ScanState::ZoomedOut);

    // TargetFollow → ZoomedOut via OperatorReleaseFollow
    let _ = h
        .submit_trigger(Trigger::PoiSelected {
            roi: Uuid::new_v4(),
            now_ns: 500,
        })
        .await;
    let _ = h
        .submit_trigger(Trigger::TargetConfirmed {
            target_id: Uuid::new_v4(),
            now_ns: 600,
        })
        .await;
    let o = h.submit_trigger(Trigger::OperatorReleaseFollow).await;
    assert!(o.accepted);
    assert_eq!(h.state().await, ScanState::ZoomedOut);

    // OperatorAbort from TargetFollow
    let _ = h
        .submit_trigger(Trigger::PoiSelected {
            roi: Uuid::new_v4(),
            now_ns: 700,
        })
        .await;
    let _ = h
        .submit_trigger(Trigger::TargetConfirmed {
            target_id: Uuid::new_v4(),
            now_ns: 800,
        })
        .await;
    let o = h.submit_trigger(Trigger::OperatorAbort).await;
    assert!(o.accepted);
    assert_eq!(h.state().await, ScanState::ZoomedOut);
}

/// AC-3 — spec-disallowed transitions are rejected with the
/// `UnsupportedTransition` reason (not silently no-ops).
#[tokio::test]
async fn ac3_unsupported_transitions_are_rejected() {
    // Arrange
    let h = ScanController::new().handle();

    // Act — TargetConfirmed makes no sense while ZoomedOut.
    let o = h
        .submit_trigger(Trigger::TargetConfirmed {
            target_id: Uuid::new_v4(),
            now_ns: 0,
        })
        .await;

    // Assert
    assert!(!o.accepted);
    assert_eq!(o.reject_reason, Some(RejectReason::UnsupportedTransition));
    assert_eq!(o.next, ScanState::ZoomedOut);
}

/// AC-4 — frame-rate floor suppresses zoom-in; once cleared, zoom-in
/// transitions resume.
#[tokio::test]
async fn ac4_frame_rate_floor_suppresses_then_clears() {
    // Arrange — feed 5 fps until the guard activates.
    let h = ScanController::new().handle();
    for i in 0..6u64 {
        h.observe_frame_at(i * 200_000_000).await;
    }
    assert!(h.fps_floor_active().await);

    // Act — PoiSelected must be suppressed.
    let o: TransitionOutcome = h
        .submit_trigger(Trigger::PoiSelected {
            roi: Uuid::new_v4(),
            now_ns: 1_500_000_000,
        })
        .await;
    assert!(!o.accepted);
    assert_eq!(o.reject_reason, Some(RejectReason::FpsFloor));

    // Recovery — feed 30 fps for 2 seconds; floor must clear.
    let start = 2_000_000_000u64;
    let step = (1e9_f64 / 30.0) as u64;
    for i in 0..60u64 {
        h.observe_frame_at(start + i * step).await;
    }
    assert!(!h.fps_floor_active().await);

    // The same PoiSelected MUST now succeed.
    let o = h
        .submit_trigger(Trigger::PoiSelected {
            roi: Uuid::new_v4(),
            now_ns: 3_000_000_000,
        })
        .await;
    assert!(o.accepted);
    assert!(matches!(h.state().await, ScanState::ZoomedIn { .. }));
}

/// AC-5 — tick latency stays well under the 10 ms p99 budget under
/// a steady-state trigger load. This bench is a smoke test, not a
/// rigorous benchmark — it exists to catch a regression that
/// silently blows past the budget.
#[tokio::test]
async fn ac5_tick_latency_p99_under_budget() {
    // Arrange
    let h = ScanController::new().handle();

    // Act — run 200 triggers through the FSM.
    for i in 0..200u64 {
        let _ = h
            .submit_trigger(Trigger::PoiSelected {
                roi: Uuid::new_v4(),
                now_ns: i * 1_000_000,
            })
            .await;
        let _ = h.submit_trigger(Trigger::OperatorAbort).await;
    }

    // Assert
    let p99 = h.tick_latency_p99_us().await;
    assert!(
        p99 < 10_000,
        "tick latency p99 {p99} us exceeds 10 ms budget"
    );
}