cranpose-foundation 0.22.3

Modifier-node, input, focus, text and semantics contracts for Cranpose UI
Documentation 
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use super::*;

#[test]
fn test_empty_tracker_returns_zero() {
    let tracker = VelocityTracker1D::new();
    assert_eq!(tracker.calculate_velocity(), 0.0);
}

#[test]
fn test_single_point_returns_zero() {
    let mut tracker = VelocityTracker1D::new();
    tracker.add_data_point(0, 100.0);
    assert_eq!(tracker.calculate_velocity(), 0.0);
}

#[test]
fn test_constant_velocity() {
    let mut tracker = VelocityTracker1D::new();
    tracker.add_data_point(0, 0.0);
    tracker.add_data_point(10, 100.0);
    tracker.add_data_point(20, 200.0);
    tracker.add_data_point(30, 300.0);

    let velocity = tracker.calculate_velocity();
    assert!(
        (velocity - 10000.0).abs() < 1000.0,
        "Expected ~10000, got {velocity}"
    );
}

#[test]
fn test_reset() {
    let mut tracker = VelocityTracker1D::new();
    tracker.add_data_point(0, 0.0);
    tracker.add_data_point(10, 100.0);

    tracker.reset();

    assert_eq!(tracker.calculate_velocity(), 0.0);
}

#[test]
fn test_negative_velocity() {
    let mut tracker = VelocityTracker1D::new();
    tracker.add_data_point(0, 300.0);
    tracker.add_data_point(10, 200.0);
    tracker.add_data_point(20, 100.0);

    let velocity = tracker.calculate_velocity();
    assert!(velocity < 0.0, "Expected negative velocity, got {velocity}");
}

#[test]
fn test_velocity_capped() {
    let mut tracker = VelocityTracker1D::new();
    tracker.add_data_point(0, 0.0);
    tracker.add_data_point(1, 10_000.0);
    tracker.add_data_point(2, 20_000.0);

    let velocity = tracker.calculate_velocity_with_max(8_000.0);
    assert_eq!(velocity, 8_000.0);

    tracker.reset();
    tracker.add_data_point(0, 20_000.0);
    tracker.add_data_point(1, 10_000.0);
    tracker.add_data_point(2, 0.0);

    let velocity = tracker.calculate_velocity_with_max(8_000.0);
    assert_eq!(velocity, -8_000.0);
}

#[test]
fn test_old_samples_ignored() {
    let mut tracker = VelocityTracker1D::new();
    tracker.add_data_point(0, 0.0);
    tracker.add_data_point(150, 100.0);
    tracker.add_data_point(160, 200.0);
    tracker.add_data_point(170, 300.0);

    let velocity = tracker.calculate_velocity();
    assert!(
        velocity.abs() > 0.0,
        "Should calculate velocity from recent samples"
    );
}

#[test]
fn test_gap_over_stopped_threshold_returns_zero() {
    let mut tracker = VelocityTracker1D::new();
    tracker.add_data_point(0, 0.0);
    tracker.add_data_point(ASSUME_STOPPED_MS + 1, 100.0);

    let velocity = tracker.calculate_velocity();
    assert_eq!(velocity, 0.0);
}

// A track of positions 8 ms apart, the last one first.
fn velocity_of(positions: &[f32]) -> f32 {
    let mut tracker = VelocityTracker1D::new();
    for (index, position) in positions.iter().enumerate() {
        tracker.add_data_point(index as i64 * 8, *position);
    }
    tracker.calculate_velocity()
}

// A finger that lifts often moves a little back first. An iOS scroll view
// gives that last move a twentieth of the weight, so the fling goes on the
// way the finger scrolled.
#[test]
fn a_small_move_back_at_the_end_keeps_the_fling_s_direction() {
    // 1,000 units a second, then 8 units back in the last sample:
    // 0.6 * 1000 + 0.35 * 1000 - 0.05 * 1000.
    let velocity = velocity_of(&[0.0, 8.0, 16.0, 24.0, 32.0, 24.0]);
    assert!((velocity - 900.0).abs() < 1.0, "{velocity}");
    // 250 units a second, then 6 units back: 0.95 * 250 - 0.05 * 750.
    let velocity = velocity_of(&[0.0, 2.0, 4.0, 6.0, 8.0, 2.0]);
    assert!((velocity - 200.0).abs() < 1.0, "{velocity}");
}

#[test]
fn a_pointer_that_stops_in_its_last_sample_keeps_most_of_its_speed() {
    let moving = velocity_of(&[0.0, 8.0, 16.0, 24.0, 32.0, 40.0]);
    let stopped = velocity_of(&[0.0, 8.0, 16.0, 24.0, 32.0, 32.0]);
    assert!((moving - 1_000.0).abs() < 1.0, "{moving}");
    assert!((stopped - 950.0).abs() < 1.0, "{stopped}");
}

#[test]
fn motion_before_a_rest_is_no_part_of_the_velocity() {
    let mut tracker = VelocityTracker1D::new();
    // Fast, a rest of 200 ms, then two slow samples.
    for (time, position) in [(0, 0.0), (8, 80.0), (16, 160.0), (216, 160.0), (224, 161.0)] {
        tracker.add_data_point(time, position);
    }
    // Only the pair after the rest counts: 0.05 * 125.
    let velocity = tracker.calculate_velocity();
    assert!((velocity - 6.25).abs() < 0.1, "{velocity}");
}