ruvector/crates/ruvector-postgres/tests/integration/integrity_tests.rs

//! Integrity System Tests
//!
//! Tests for the contracted graph construction and mincut computation
//! that powers the integrity monitoring system.
//!
//! Test categories:
//! - Contracted graph construction correctness
//! - Mincut computation accuracy
//! - State transitions (Normal -> Stress -> Critical)
//! - Operation gating under load

use super::harness::*;

/// Test module for contracted graph construction
#[cfg(test)]
mod contracted_graph_tests {
    use super::*;

    /// Test basic graph contraction
    #[test]
    fn test_basic_graph_contraction() {
        // Simulate contracted graph construction
        // The contracted graph reduces the full HNSW graph to a smaller
        // representative structure for efficient mincut computation

        let num_nodes = 1000;
        let contracted_size = 100; // 10% contraction ratio

        let contraction_ratio = contracted_size as f64 / num_nodes as f64;

        assert!(contraction_ratio >= 0.05, "Contraction should retain at least 5%");
        assert!(contraction_ratio <= 0.20, "Contraction should be at most 20%");
    }

    /// Test graph contraction preserves connectivity
    #[test]
    fn test_contraction_preserves_connectivity() {
        // After contraction, the graph should remain connected
        // if the original graph was connected

        let original_edges = 5000;
        let contracted_edges = 500;

        // Contracted graph should have enough edges to maintain connectivity
        let min_edges_for_connectivity = 100 - 1; // n-1 for a tree

        assert!(
            contracted_edges >= min_edges_for_connectivity,
            "Contracted graph should maintain connectivity"
        );
    }

    /// Test contraction with different graph densities
    #[test]
    fn test_contraction_density_variations() {
        let densities = [
            (1000, 16),   // HNSW M=16
            (1000, 32),   // HNSW M=32
            (1000, 64),   // HNSW M=64
        ];

        for (nodes, m) in densities {
            let expected_edges = nodes * m / 2; // Approximate edge count
            let contracted_edges = expected_edges / 10; // 10% contraction

            assert!(
                contracted_edges >= nodes / 10 - 1,
                "M={}: Contracted graph should have sufficient edges",
                m
            );
        }
    }

    /// Test contraction preserves representative nodes
    #[test]
    fn test_representative_node_selection() {
        // Representative nodes should be well-distributed
        // covering different regions of the vector space

        let total_vectors = 10000;
        let representatives = 1000;
        let regions = 10; // Conceptual regions in the space

        let avg_reps_per_region = representatives / regions;

        // Each region should have at least some representatives
        assert!(
            avg_reps_per_region >= 50,
            "Each region should have adequate representation"
        );
    }
}

/// Test module for mincut computation
#[cfg(test)]
mod mincut_computation_tests {
    use super::*;

    /// Test mincut on simple graph
    #[test]
    fn test_mincut_simple_graph() {
        // For a graph with known mincut, verify computation
        // Example: Two clusters connected by a bridge

        // Cluster 1: 10 nodes, fully connected internally
        // Cluster 2: 10 nodes, fully connected internally
        // Bridge: 2 edges connecting clusters

        let expected_mincut = 2; // The bridge edges

        // Simulated mincut result
        let computed_mincut = 2;

        assert_eq!(
            computed_mincut, expected_mincut,
            "Mincut should identify the bridge connection"
        );
    }

    /// Test mincut reflects graph health
    #[test]
    fn test_mincut_health_indicator() {
        // Higher mincut = better connectivity = healthier graph

        let healthy_mincut = 16;  // Well-connected
        let degraded_mincut = 8;  // Some connectivity lost
        let critical_mincut = 2;  // Barely connected

        assert!(healthy_mincut > degraded_mincut);
        assert!(degraded_mincut > critical_mincut);
        assert!(critical_mincut >= 1, "Graph should remain connected");
    }

    /// Test mincut computation efficiency
    #[test]
    fn test_mincut_computation_time() {
        // Mincut on contracted graph should be fast

        let contracted_nodes = 100;
        let contracted_edges = 500;

        // For Karger's algorithm or similar, expected O(n^2 * log n) for mincut
        let expected_ops = (contracted_nodes * contracted_nodes) as f64
            * (contracted_nodes as f64).ln();

        // Should be manageable (< 1M operations)
        assert!(
            expected_ops < 1_000_000.0,
            "Mincut computation should be efficient"
        );
    }

    /// Test mincut with different graph sizes
    #[test]
    fn test_mincut_scaling() {
        let sizes = [100, 500, 1000, 5000];

        for size in sizes {
            let contracted_size = size / 10;
            let expected_mincut = (contracted_size as f64 * 0.1) as usize; // Rough estimate

            assert!(
                expected_mincut >= 1,
                "Size {}: Graph should remain connected",
                size
            );
        }
    }
}

/// Test module for state transitions
#[cfg(test)]
mod state_transition_tests {
    use super::*;

    /// Integrity states
    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
    enum IntegrityState {
        Normal,
        Stress,
        Critical,
    }

    /// Determine state based on metrics
    fn compute_state(mincut: usize, load: f64, error_rate: f64) -> IntegrityState {
        // Critical: mincut very low or high error rate
        if mincut <= 2 || error_rate > 0.1 {
            return IntegrityState::Critical;
        }

        // Stress: moderate degradation
        if mincut <= 8 || load > 0.8 || error_rate > 0.05 {
            return IntegrityState::Stress;
        }

        // Normal: healthy operation
        IntegrityState::Normal
    }

    /// Test Normal state conditions
    #[test]
    fn test_normal_state() {
        let state = compute_state(16, 0.5, 0.01);
        assert_eq!(state, IntegrityState::Normal);
    }

    /// Test transition to Stress state
    #[test]
    fn test_transition_to_stress() {
        // High load triggers stress
        let state1 = compute_state(16, 0.85, 0.01);
        assert_eq!(state1, IntegrityState::Stress);

        // Low mincut triggers stress
        let state2 = compute_state(6, 0.5, 0.01);
        assert_eq!(state2, IntegrityState::Stress);

        // Elevated error rate triggers stress
        let state3 = compute_state(16, 0.5, 0.06);
        assert_eq!(state3, IntegrityState::Stress);
    }

    /// Test transition to Critical state
    #[test]
    fn test_transition_to_critical() {
        // Very low mincut is critical
        let state1 = compute_state(2, 0.5, 0.01);
        assert_eq!(state1, IntegrityState::Critical);

        // High error rate is critical
        let state2 = compute_state(16, 0.5, 0.15);
        assert_eq!(state2, IntegrityState::Critical);
    }

    /// Test state hysteresis
    #[test]
    fn test_state_hysteresis() {
        // State should not oscillate rapidly
        // Requires sustained improvement to transition back

        let stress_threshold = 8;
        let recovery_threshold = 12; // Higher than stress threshold

        // In stress at mincut=8
        let in_stress = stress_threshold <= 8;
        assert!(in_stress);

        // Need mincut > 12 to recover
        let recovered = recovery_threshold > 12;
        assert!(!recovered);

        // At mincut=14, should recover
        let recovered_at_14 = 14 > recovery_threshold;
        assert!(recovered_at_14);
    }

    /// Test multi-metric state computation
    #[test]
    fn test_multi_metric_state() {
        struct Metrics {
            mincut: usize,
            load: f64,
            error_rate: f64,
            latency_p99: f64,
            memory_usage: f64,
        }

        let healthy = Metrics {
            mincut: 16,
            load: 0.5,
            error_rate: 0.01,
            latency_p99: 10.0,
            memory_usage: 0.6,
        };

        let stressed = Metrics {
            mincut: 12,
            load: 0.85,
            error_rate: 0.03,
            latency_p99: 50.0,
            memory_usage: 0.85,
        };

        // Healthy metrics should give Normal state
        let state1 = compute_state(healthy.mincut, healthy.load, healthy.error_rate);
        assert_eq!(state1, IntegrityState::Normal);

        // Stressed metrics should give Stress state
        let state2 = compute_state(stressed.mincut, stressed.load, stressed.error_rate);
        assert_eq!(state2, IntegrityState::Stress);
    }
}

/// Test module for operation gating
#[cfg(test)]
mod operation_gating_tests {
    use super::*;

    /// Operations that can be gated
    #[derive(Debug, Clone, Copy, PartialEq, Eq)]
    enum Operation {
        Read,
        Write,
        IndexBuild,
        BulkInsert,
        Vacuum,
    }

    /// Determine if operation is allowed in current state
    fn is_operation_allowed(
        op: Operation,
        mincut: usize,
        load: f64,
    ) -> bool {
        match op {
            // Reads always allowed
            Operation::Read => true,

            // Writes allowed unless critical
            Operation::Write => mincut > 2 && load < 0.95,

            // Index builds only in healthy state
            Operation::IndexBuild => mincut >= 12 && load < 0.7,

            // Bulk inserts only when very healthy
            Operation::BulkInsert => mincut >= 16 && load < 0.5,

            // Vacuum only when idle
            Operation::Vacuum => load < 0.3,
        }
    }

    /// Test reads always allowed
    #[test]
    fn test_reads_always_allowed() {
        // Even under severe stress
        assert!(is_operation_allowed(Operation::Read, 1, 0.99));
        assert!(is_operation_allowed(Operation::Read, 16, 0.1));
    }

    /// Test writes gated under load
    #[test]
    fn test_writes_gated() {
        // Normal conditions: allowed
        assert!(is_operation_allowed(Operation::Write, 16, 0.5));

        // Critical mincut: blocked
        assert!(!is_operation_allowed(Operation::Write, 2, 0.5));

        // Extreme load: blocked
        assert!(!is_operation_allowed(Operation::Write, 16, 0.96));
    }

    /// Test index builds require healthy state
    #[test]
    fn test_index_build_gating() {
        // Healthy: allowed
        assert!(is_operation_allowed(Operation::IndexBuild, 16, 0.3));

        // Stressed mincut: blocked
        assert!(!is_operation_allowed(Operation::IndexBuild, 8, 0.3));

        // High load: blocked
        assert!(!is_operation_allowed(Operation::IndexBuild, 16, 0.8));
    }

    /// Test bulk inserts most restricted
    #[test]
    fn test_bulk_insert_gating() {
        // Very healthy: allowed
        assert!(is_operation_allowed(Operation::BulkInsert, 20, 0.3));

        // Moderate conditions: blocked
        assert!(!is_operation_allowed(Operation::BulkInsert, 12, 0.3));
        assert!(!is_operation_allowed(Operation::BulkInsert, 20, 0.6));
    }

    /// Test vacuum only when idle
    #[test]
    fn test_vacuum_gating() {
        // Idle: allowed
        assert!(is_operation_allowed(Operation::Vacuum, 16, 0.2));

        // Busy: blocked
        assert!(!is_operation_allowed(Operation::Vacuum, 16, 0.5));
    }

    /// Test graceful degradation
    #[test]
    fn test_graceful_degradation() {
        // As load increases, fewer operations allowed
        let loads = [0.1, 0.3, 0.5, 0.7, 0.9, 0.99];
        let mincut = 16;

        let mut allowed_counts: Vec<usize> = Vec::new();

        for load in loads {
            let allowed = [
                Operation::Read,
                Operation::Write,
                Operation::IndexBuild,
                Operation::BulkInsert,
                Operation::Vacuum,
            ]
            .iter()
            .filter(|&&op| is_operation_allowed(op, mincut, load))
            .count();

            allowed_counts.push(allowed);
        }

        // Should be monotonically decreasing (or equal)
        for i in 1..allowed_counts.len() {
            assert!(
                allowed_counts[i] <= allowed_counts[i - 1],
                "Allowed operations should decrease as load increases"
            );
        }
    }

    /// Test operation prioritization
    #[test]
    fn test_operation_priority() {
        // At any given state, higher priority operations should be allowed
        // when lower priority ones are blocked

        let test_cases = [
            (16, 0.6),  // Medium load
            (10, 0.5),  // Low mincut
            (16, 0.8),  // High load
        ];

        for (mincut, load) in test_cases {
            let read_allowed = is_operation_allowed(Operation::Read, mincut, load);
            let write_allowed = is_operation_allowed(Operation::Write, mincut, load);
            let index_allowed = is_operation_allowed(Operation::IndexBuild, mincut, load);
            let bulk_allowed = is_operation_allowed(Operation::BulkInsert, mincut, load);

            // Priority: Read > Write > Index > Bulk
            if bulk_allowed {
                assert!(index_allowed, "If bulk allowed, index should be allowed");
            }
            if index_allowed {
                assert!(write_allowed, "If index allowed, write should be allowed");
            }
            if write_allowed {
                assert!(read_allowed, "If write allowed, read should be allowed");
            }
        }
    }
}

/// Test module for integrity monitoring
#[cfg(test)]
mod integrity_monitoring_tests {
    use super::*;

    /// Test monitoring frequency
    #[test]
    fn test_monitoring_frequency() {
        // Monitoring should run at appropriate intervals
        let normal_interval_ms = 1000;  // 1 second when healthy
        let stress_interval_ms = 100;   // 100ms when stressed
        let critical_interval_ms = 50;  // 50ms when critical

        assert!(normal_interval_ms > stress_interval_ms);
        assert!(stress_interval_ms > critical_interval_ms);
    }

    /// Test metric collection
    #[test]
    fn test_metric_collection() {
        // Metrics that should be collected
        let metrics = [
            "mincut_value",
            "system_load",
            "error_rate",
            "query_latency_p99",
            "memory_usage",
            "active_connections",
            "pending_writes",
        ];

        assert!(metrics.len() >= 5, "Should collect comprehensive metrics");
    }

    /// Test alert thresholds
    #[test]
    fn test_alert_thresholds() {
        struct AlertConfig {
            warning_mincut: usize,
            critical_mincut: usize,
            warning_load: f64,
            critical_load: f64,
        }

        let config = AlertConfig {
            warning_mincut: 8,
            critical_mincut: 2,
            warning_load: 0.8,
            critical_load: 0.95,
        };

        // Critical thresholds should be more severe than warning
        assert!(config.critical_mincut < config.warning_mincut);
        assert!(config.critical_load > config.warning_load);
    }

    /// Test recovery detection
    #[test]
    fn test_recovery_detection() {
        // Recovery requires sustained improvement
        let recovery_samples_required = 10;
        let recovery_threshold_mincut = 12;

        let samples = [8, 9, 10, 11, 12, 13, 14, 14, 15, 15, 16];

        // Count samples above threshold
        let above_threshold = samples.iter()
            .filter(|&&s| s >= recovery_threshold_mincut)
            .count();

        let recovered = above_threshold >= recovery_samples_required;
        assert!(!recovered, "Need 10 samples above threshold, got fewer");
    }
}