Squashed 'vendor/ruvector/' content from commit b64c2172

git-subtree-dir: vendor/ruvector
git-subtree-split: b64c21726f2bb37286d9ee36a7869fef60cc6900

examples/data/framework/tests/dynamic_mincut_tests.rs

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+//! Comprehensive test suite for dynamic min-cut tracking system
+//!
+//! Tests cover:
+//! - Euler tour tree operations (link, cut, connectivity)
+//! - DynamicCutWatcher edge updates and threshold detection
+//! - Local min-cut procedures and weak region detection
+//! - Cut-gated search and expansion pruning
+//! - Integration tests with real vectors
+//! - Correctness verification against static algorithms
+//! - Concurrent operations and stress testing
+
+use std::collections::{HashMap, HashSet};
+use std::sync::{Arc, Mutex};
+use std::thread;
+
+// ===== Mock Structures for Testing =====
+// In production, these would be imported from ruvector-mincut
+
+/// Mock Euler Tour Tree for testing
+#[derive(Clone)]
+struct MockEulerTourTree {
+    vertices: HashSet<u64>,
+    edges: HashSet<(u64, u64)>,
+    connected_components: HashMap<u64, usize>,
+}
+
+impl MockEulerTourTree {
+    fn new() -> Self {
+        Self {
+            vertices: HashSet::new(),
+            edges: HashSet::new(),
+            connected_components: HashMap::new(),
+        }
+    }
+
+    fn make_tree(&mut self, v: u64) {
+        self.vertices.insert(v);
+        self.connected_components.insert(v, v as usize);
+    }
+
+    fn link(&mut self, u: u64, v: u64) {
+        self.edges.insert((u.min(v), u.max(v)));
+        // Merge components
+        let u_comp = *self.connected_components.get(&u).unwrap();
+        let v_comp = *self.connected_components.get(&v).unwrap();
+        for (_, comp) in self.connected_components.iter_mut() {
+            if *comp == v_comp {
+                *comp = u_comp;
+            }
+        }
+    }
+
+    fn cut(&mut self, u: u64, v: u64) {
+        self.edges.remove(&(u.min(v), u.max(v)));
+        // Recompute components (simplified)
+        self.recompute_components();
+    }
+
+    fn connected(&self, u: u64, v: u64) -> bool {
+        self.connected_components.get(&u) == self.connected_components.get(&v)
+    }
+
+    fn tree_size(&self, v: u64) -> usize {
+        let comp = self.connected_components.get(&v).unwrap();
+        self.connected_components.values().filter(|&c| c == comp).count()
+    }
+
+    fn recompute_components(&mut self) {
+        // Reset components
+        for (&v, comp) in self.connected_components.iter_mut() {
+            *comp = v as usize;
+        }
+
+        // Union-find style merging based on edges
+        for &(u, v) in &self.edges {
+            let u_comp = *self.connected_components.get(&u).unwrap();
+            let v_comp = *self.connected_components.get(&v).unwrap();
+            for (_, comp) in self.connected_components.iter_mut() {
+                if *comp == v_comp {
+                    *comp = u_comp;
+                }
+            }
+        }
+    }
+}
+
+/// Mock Dynamic Cut Watcher
+struct MockDynamicCutWatcher {
+    current_cut: f64,
+    threshold: f64,
+    updates_count: usize,
+    needs_recompute: bool,
+}
+
+impl MockDynamicCutWatcher {
+    fn new(initial_cut: f64, threshold: f64) -> Self {
+        Self {
+            current_cut: initial_cut,
+            threshold,
+            updates_count: 0,
+            needs_recompute: false,
+        }
+    }
+
+    fn insert_edge(&mut self, _u: u64, _v: u64, weight: f64) {
+        self.updates_count += 1;
+        // Adding edge can only increase or maintain cut
+        self.current_cut = self.current_cut.max(weight);
+        self.check_threshold();
+    }
+
+    fn delete_edge(&mut self, _u: u64, _v: u64, weight: f64) {
+        self.updates_count += 1;
+        // Deleting edge may decrease cut - need to check
+        if (self.current_cut - weight).abs() < 0.001 {
+            self.needs_recompute = true;
+        }
+        self.check_threshold();
+    }
+
+    fn current_mincut(&self) -> f64 {
+        self.current_cut
+    }
+
+    fn check_threshold(&mut self) {
+        if self.updates_count >= self.threshold as usize {
+            self.needs_recompute = true;
+        }
+    }
+
+    fn trigger_recompute(&mut self) {
+        self.needs_recompute = false;
+        self.updates_count = 0;
+    }
+}
+
+// ===== Test Modules =====
+
+#[cfg(test)]
+mod euler_tour_tests {
+    use super::*;
+
+    #[test]
+    fn test_link_cut_basic() {
+        let mut ett = MockEulerTourTree::new();
+
+        // Create vertices
+        ett.make_tree(1);
+        ett.make_tree(2);
+        ett.make_tree(3);
+
+        // Initially disconnected
+        assert!(!ett.connected(1, 2));
+        assert!(!ett.connected(2, 3));
+        assert!(!ett.connected(1, 3));
+
+        // Link 1-2
+        ett.link(1, 2);
+        assert!(ett.connected(1, 2));
+        assert!(!ett.connected(2, 3));
+
+        // Link 2-3
+        ett.link(2, 3);
+        assert!(ett.connected(1, 2));
+        assert!(ett.connected(2, 3));
+        assert!(ett.connected(1, 3));
+
+        // Cut 2-3
+        ett.cut(2, 3);
+        assert!(ett.connected(1, 2));
+        assert!(!ett.connected(2, 3));
+        assert!(!ett.connected(1, 3));
+    }
+
+    #[test]
+    fn test_connectivity_queries() {
+        let mut ett = MockEulerTourTree::new();
+
+        for i in 1..=10 {
+            ett.make_tree(i);
+        }
+
+        // Create chain: 1-2-3-4-5
+        ett.link(1, 2);
+        ett.link(2, 3);
+        ett.link(3, 4);
+        ett.link(4, 5);
+
+        // Create separate chain: 6-7-8
+        ett.link(6, 7);
+        ett.link(7, 8);
+
+        // Test connectivity within components
+        assert!(ett.connected(1, 5));
+        assert!(ett.connected(6, 8));
+        assert!(!ett.connected(1, 6));
+        assert!(!ett.connected(5, 8));
+
+        // Test single vertices
+        assert!(!ett.connected(9, 10));
+        assert!(!ett.connected(1, 9));
+    }
+
+    #[test]
+    fn test_component_sizes() {
+        let mut ett = MockEulerTourTree::new();
+
+        for i in 1..=6 {
+            ett.make_tree(i);
+        }
+
+        // Component 1: vertices 1,2,3
+        ett.link(1, 2);
+        ett.link(2, 3);
+
+        // Component 2: vertices 4,5,6
+        ett.link(4, 5);
+        ett.link(5, 6);
+
+        assert_eq!(ett.tree_size(1), 3);
+        assert_eq!(ett.tree_size(2), 3);
+        assert_eq!(ett.tree_size(3), 3);
+        assert_eq!(ett.tree_size(4), 3);
+        assert_eq!(ett.tree_size(5), 3);
+        assert_eq!(ett.tree_size(6), 3);
+    }
+
+    #[test]
+    fn test_concurrent_operations() {
+        let ett = Arc::new(Mutex::new(MockEulerTourTree::new()));
+
+        // Initialize vertices
+        {
+            let mut ett_lock = ett.lock().unwrap();
+            for i in 1..=20 {
+                ett_lock.make_tree(i);
+            }
+        }
+
+        // Spawn threads to perform operations
+        let handles: Vec<_> = (0..4)
+            .map(|thread_id| {
+                let ett_clone = Arc::clone(&ett);
+                thread::spawn(move || {
+                    let mut ett_lock = ett_clone.lock().unwrap();
+                    let base = thread_id * 5;
+                    for i in 0..4 {
+                        ett_lock.link(base + i + 1, base + i + 2);
+                    }
+                })
+            })
+            .collect();
+
+        for handle in handles {
+            handle.join().unwrap();
+        }
+
+        // Verify all components are created
+        let ett_lock = ett.lock().unwrap();
+        assert!(ett_lock.connected(1, 5));
+        assert!(ett_lock.connected(6, 10));
+        assert!(ett_lock.connected(11, 15));
+        assert!(ett_lock.connected(16, 20));
+    }
+
+    #[test]
+    fn test_large_graph_performance() {
+        let mut ett = MockEulerTourTree::new();
+        let n = 1000;
+
+        // Create vertices
+        for i in 0..n {
+            ett.make_tree(i);
+        }
+
+        // Create star topology: 0 connected to all others
+        for i in 1..n {
+            ett.link(0, i);
+        }
+
+        // Verify all connected
+        for i in 1..n {
+            assert!(ett.connected(0, i));
+        }
+
+        assert_eq!(ett.tree_size(0), n as usize);
+    }
+}
+
+#[cfg(test)]
+mod cut_watcher_tests {
+    use super::*;
+
+    #[test]
+    fn test_edge_insert_updates_cut() {
+        let mut watcher = MockDynamicCutWatcher::new(5.0, 100.0);
+
+        assert_eq!(watcher.current_mincut(), 5.0);
+
+        watcher.insert_edge(1, 2, 3.0);
+        assert_eq!(watcher.current_mincut(), 5.0); // No decrease
+
+        watcher.insert_edge(2, 3, 7.0);
+        assert_eq!(watcher.current_mincut(), 7.0); // Increased
+    }
+
+    #[test]
+    fn test_edge_delete_updates_cut() {
+        let mut watcher = MockDynamicCutWatcher::new(5.0, 100.0);
+
+        watcher.delete_edge(1, 2, 3.0);
+        assert!(!watcher.needs_recompute); // Not critical edge
+
+        watcher.delete_edge(2, 3, 5.0);
+        assert!(watcher.needs_recompute); // Critical edge deleted
+    }
+
+    #[test]
+    fn test_cut_sensitivity_detection() {
+        let mut watcher = MockDynamicCutWatcher::new(10.0, 50.0);
+
+        // Perform updates
+        for i in 0..45 {
+            watcher.insert_edge(i, i + 1, 1.0);
+        }
+
+        assert!(!watcher.needs_recompute);
+
+        // Cross threshold
+        for i in 45..55 {
+            watcher.insert_edge(i, i + 1, 1.0);
+        }
+
+        assert!(watcher.needs_recompute);
+    }
+
+    #[test]
+    fn test_threshold_triggering() {
+        let mut watcher = MockDynamicCutWatcher::new(5.0, 10.0);
+
+        for i in 0..9 {
+            watcher.insert_edge(i, i + 1, 1.0);
+        }
+        assert!(!watcher.needs_recompute);
+
+        watcher.insert_edge(9, 10, 1.0);
+        assert!(watcher.needs_recompute);
+    }
+
+    #[test]
+    fn test_recompute_fallback() {
+        let mut watcher = MockDynamicCutWatcher::new(5.0, 10.0);
+
+        // Trigger recompute
+        for i in 0..15 {
+            watcher.insert_edge(i, i + 1, 1.0);
+        }
+
+        assert!(watcher.needs_recompute);
+
+        // Recompute
+        watcher.trigger_recompute();
+        assert!(!watcher.needs_recompute);
+        assert_eq!(watcher.updates_count, 0);
+    }
+
+    #[test]
+    fn test_concurrent_updates() {
+        let watcher = Arc::new(Mutex::new(MockDynamicCutWatcher::new(10.0, 100.0)));
+
+        let handles: Vec<_> = (0..4)
+            .map(|thread_id| {
+                let watcher_clone = Arc::clone(&watcher);
+                thread::spawn(move || {
+                    for i in 0..25 {
+                        let mut w = watcher_clone.lock().unwrap();
+                        w.insert_edge(thread_id * 100 + i, thread_id * 100 + i + 1, 1.0);
+                    }
+                })
+            })
+            .collect();
+
+        for handle in handles {
+            handle.join().unwrap();
+        }
+
+        let w = watcher.lock().unwrap();
+        assert_eq!(w.updates_count, 100);
+        assert!(w.needs_recompute);
+    }
+}
+
+#[cfg(test)]
+mod local_mincut_tests {
+    use super::*;
+
+    #[test]
+    fn test_local_cut_basic() {
+        // Simulate local min-cut computation
+        let graph = create_test_graph(10, 0.3);
+        let local_cut = compute_local_mincut(&graph, 0, 3);
+
+        assert!(local_cut > 0.0);
+        assert!(local_cut < f64::INFINITY);
+    }
+
+    #[test]
+    fn test_weak_region_detection() {
+        let graph = create_bottleneck_graph(20);
+        let weak_region = detect_weak_region(&graph, 0);
+
+        assert!(!weak_region.is_empty());
+        assert!(weak_region.len() < 20);
+    }
+
+    #[test]
+    fn test_ball_growing() {
+        let graph = create_test_graph(50, 0.2);
+        let ball = grow_ball_from_vertex(&graph, 0, 5);
+
+        assert!(ball.contains(&0));
+        assert!(ball.len() <= 5);
+    }
+
+    #[test]
+    fn test_conductance_threshold() {
+        let graph = create_expander_graph(30);
+        let conductance = compute_conductance(&graph, &[0, 1, 2, 3, 4]);
+
+        assert!(conductance > 0.0);
+        assert!(conductance <= 1.0);
+    }
+
+    // Helper functions
+
+    fn create_test_graph(n: usize, _density: f64) -> HashMap<usize, Vec<usize>> {
+        let mut graph = HashMap::new();
+        for i in 0..n {
+            graph.insert(i, vec![(i + 1) % n, (i + 2) % n]);
+        }
+        graph
+    }
+
+    fn create_bottleneck_graph(n: usize) -> HashMap<usize, Vec<usize>> {
+        let mut graph = HashMap::new();
+        let half = n / 2;
+
+        // Dense left side
+        for i in 0..half {
+            graph.insert(i, (0..half).filter(|&j| j != i).collect());
+        }
+
+        // Dense right side
+        for i in half..n {
+            graph.insert(i, (half..n).filter(|&j| j != i).collect());
+        }
+
+        // Single bottleneck edge
+        graph.get_mut(&(half - 1)).unwrap().push(half);
+        graph.get_mut(&half).unwrap().push(half - 1);
+
+        graph
+    }
+
+    fn create_expander_graph(n: usize) -> HashMap<usize, Vec<usize>> {
+        let mut graph = HashMap::new();
+        for i in 0..n {
+            graph.insert(
+                i,
+                vec![(i + 1) % n, (i + 2) % n, (i + 5) % n, (i + 11) % n],
+            );
+        }
+        graph
+    }
+
+    fn compute_local_mincut(graph: &HashMap<usize, Vec<usize>>, source: usize, radius: usize) -> f64 {
+        let ball = grow_ball_from_vertex(graph, source, radius);
+        compute_conductance(graph, &ball)
+    }
+
+    fn detect_weak_region(graph: &HashMap<usize, Vec<usize>>, start: usize) -> Vec<usize> {
+        grow_ball_from_vertex(graph, start, 5)
+    }
+
+    fn grow_ball_from_vertex(
+        graph: &HashMap<usize, Vec<usize>>,
+        start: usize,
+        max_radius: usize,
+    ) -> Vec<usize> {
+        let mut ball = vec![start];
+        let mut visited = HashSet::new();
+        visited.insert(start);
+
+        for _ in 0..max_radius {
+            let mut new_vertices = Vec::new();
+            for &v in &ball {
+                if let Some(neighbors) = graph.get(&v) {
+                    for &neighbor in neighbors {
+                        if visited.insert(neighbor) {
+                            new_vertices.push(neighbor);
+                        }
+                    }
+                }
+            }
+            ball.extend(new_vertices);
+        }
+
+        ball
+    }
+
+    fn compute_conductance(graph: &HashMap<usize, Vec<usize>>, subset: &[usize]) -> f64 {
+        let subset_set: HashSet<_> = subset.iter().copied().collect();
+
+        let mut cut_edges = 0;
+        let mut volume = 0;
+
+        for &v in subset {
+            if let Some(neighbors) = graph.get(&v) {
+                volume += neighbors.len();
+                for &neighbor in neighbors {
+                    if !subset_set.contains(&neighbor) {
+                        cut_edges += 1;
+                    }
+                }
+            }
+        }
+
+        if volume == 0 {
+            return 1.0;
+        }
+
+        cut_edges as f64 / volume as f64
+    }
+}
+
+#[cfg(test)]
+mod cut_gated_search_tests {
+    use super::*;
+
+    #[test]
+    fn test_gated_vs_ungated_search() {
+        let graph = create_search_graph();
+
+        // Ungated: explores all vertices
+        let ungated_visited = ungated_search(&graph, 0, 10);
+
+        // Gated: stops at cut boundaries
+        let gated_visited = gated_search(&graph, 0, 10, 2.0);
+
+        assert!(gated_visited.len() <= ungated_visited.len());
+    }
+
+    #[test]
+    fn test_expansion_pruning() {
+        let graph = create_partitioned_graph();
+        let visited = gated_search(&graph, 0, 20, 1.0);
+
+        // Should only visit one partition
+        assert!(visited.len() < 15);
+    }
+
+    #[test]
+    fn test_cross_cut_hops() {
+        let graph = create_partitioned_graph();
+        let path = find_path_respecting_cuts(&graph, 0, 25, 2.0);
+
+        // Path should avoid crossing low-conductance cuts
+        assert!(path.is_some());
+    }
+
+    #[test]
+    fn test_coherence_zones() {
+        let graph = create_clustered_graph();
+        let zones = identify_coherence_zones(&graph, 0.3);
+
+        assert!(zones.len() > 1);
+        assert!(zones.len() < 10);
+    }
+
+    // Helper functions
+
+    fn create_search_graph() -> HashMap<usize, Vec<(usize, f64)>> {
+        let mut graph = HashMap::new();
+        for i in 0..15 {
+            graph.insert(i, vec![(i + 1, 1.0), (i + 2, 1.0)]);
+        }
+        graph
+    }
+
+    fn create_partitioned_graph() -> HashMap<usize, Vec<(usize, f64)>> {
+        let mut graph = HashMap::new();
+
+        // Partition 1: 0-9
+        for i in 0..10 {
+            graph.insert(i, vec![(i + 1, 5.0), (i + 2, 5.0)]);
+        }
+
+        // Partition 2: 10-19
+        for i in 10..20 {
+            graph.insert(i, vec![(i + 1, 5.0), (i + 2, 5.0)]);
+        }
+
+        // Weak bridge
+        graph.insert(9, vec![(10, 0.5)]);
+
+        graph
+    }
+
+    fn create_clustered_graph() -> HashMap<usize, Vec<(usize, f64)>> {
+        let mut graph = HashMap::new();
+
+        for cluster in 0..3 {
+            for i in 0..10 {
+                let v = cluster * 10 + i;
+                graph.insert(v, vec![(v + 1, 10.0), (v + 2, 10.0)]);
+            }
+        }
+
+        graph
+    }
+
+    fn ungated_search(graph: &HashMap<usize, Vec<(usize, f64)>>, start: usize, max: usize) -> Vec<usize> {
+        let mut visited = vec![start];
+        let mut seen = HashSet::new();
+        seen.insert(start);
+
+        while visited.len() < max {
+            let mut found_new = false;
+            for &v in &visited.clone() {
+                if let Some(neighbors) = graph.get(&v) {
+                    for &(neighbor, _) in neighbors {
+                        if seen.insert(neighbor) {
+                            visited.push(neighbor);
+                            found_new = true;
+                            if visited.len() >= max {
+                                break;
+                            }
+                        }
+                    }
+                }
+                if visited.len() >= max {
+                    break;
+                }
+            }
+            if !found_new {
+                break;
+            }
+        }
+
+        visited
+    }
+
+    fn gated_search(
+        graph: &HashMap<usize, Vec<(usize, f64)>>,
+        start: usize,
+        max: usize,
+        min_weight: f64,
+    ) -> Vec<usize> {
+        let mut visited = vec![start];
+        let mut seen = HashSet::new();
+        seen.insert(start);
+
+        while visited.len() < max {
+            let mut found_new = false;
+            for &v in &visited.clone() {
+                if let Some(neighbors) = graph.get(&v) {
+                    for &(neighbor, weight) in neighbors {
+                        if weight >= min_weight && seen.insert(neighbor) {
+                            visited.push(neighbor);
+                            found_new = true;
+                            if visited.len() >= max {
+                                break;
+                            }
+                        }
+                    }
+                }
+                if visited.len() >= max {
+                    break;
+                }
+            }
+            if !found_new {
+                break;
+            }
+        }
+
+        visited
+    }
+
+    fn find_path_respecting_cuts(
+        graph: &HashMap<usize, Vec<(usize, f64)>>,
+        start: usize,
+        end: usize,
+        min_weight: f64,
+    ) -> Option<Vec<usize>> {
+        let visited = gated_search(graph, start, 100, min_weight);
+        if visited.contains(&end) {
+            Some(visited)
+        } else {
+            None
+        }
+    }
+
+    fn identify_coherence_zones(
+        graph: &HashMap<usize, Vec<(usize, f64)>>,
+        threshold: f64,
+    ) -> Vec<Vec<usize>> {
+        let mut zones = Vec::new();
+        let mut visited_global = HashSet::new();
+
+        for &start in graph.keys() {
+            if visited_global.contains(&start) {
+                continue;
+            }
+
+            let zone = gated_search(graph, start, 100, threshold);
+            for &v in &zone {
+                visited_global.insert(v);
+            }
+            zones.push(zone);
+        }
+
+        zones
+    }
+}
+
+#[cfg(test)]
+mod integration_tests {
+    use super::*;
+
+    #[test]
+    fn test_full_pipeline() {
+        // Create graph
+        let mut ett = MockEulerTourTree::new();
+        for i in 0..10 {
+            ett.make_tree(i);
+        }
+
+        // Build structure
+        for i in 0..9 {
+            ett.link(i, i + 1);
+        }
+
+        // Create watcher
+        let mut watcher = MockDynamicCutWatcher::new(1.0, 20.0);
+
+        // Perform updates
+        for i in 10..20 {
+            watcher.insert_edge(i, i + 1, 1.0);
+        }
+
+        // Verify state
+        assert!(ett.connected(0, 9));
+        assert_eq!(watcher.updates_count, 10);
+    }
+
+    #[test]
+    fn test_with_real_vectors() {
+        // Simulate vector database with min-cut tracking
+        let vectors = generate_test_vectors(100);
+        let graph = build_knn_graph(&vectors, 5);
+
+        let mut ett = MockEulerTourTree::new();
+        for i in 0..100 {
+            ett.make_tree(i);
+        }
+
+        for (u, v) in &graph {
+            ett.link(*u, *v);
+        }
+
+        // Verify connectivity
+        let num_components = count_components(&ett);
+        assert!(num_components >= 1);
+        assert!(num_components <= 100);
+    }
+
+    #[test]
+    fn test_streaming_updates() {
+        let mut watcher = MockDynamicCutWatcher::new(5.0, 50.0);
+
+        // Simulate streaming edge updates
+        for batch in 0..5 {
+            for i in 0..10 {
+                let edge_id = batch * 10 + i;
+                watcher.insert_edge(edge_id, edge_id + 1, 1.0);
+            }
+
+            if batch == 2 {
+                // Midway recompute
+                watcher.trigger_recompute();
+            }
+        }
+
+        assert_eq!(watcher.updates_count, 20); // 50 total - 30 before recompute
+    }
+
+    // Helper functions
+
+    fn generate_test_vectors(n: usize) -> Vec<Vec<f64>> {
+        (0..n)
+            .map(|i| vec![(i as f64) * 0.1; 128])
+            .collect()
+    }
+
+    fn build_knn_graph(vectors: &[Vec<f64>], k: usize) -> Vec<(u64, u64)> {
+        let mut edges = Vec::new();
+
+        for (i, _vec) in vectors.iter().enumerate() {
+            // Simplified: connect to next k vertices
+            for j in 1..=k {
+                if i + j < vectors.len() {
+                    edges.push((i as u64, (i + j) as u64));
+                }
+            }
+        }
+
+        edges
+    }
+
+    fn count_components(ett: &MockEulerTourTree) -> usize {
+        ett.connected_components.values().collect::<HashSet<_>>().len()
+    }
+}
+
+#[cfg(test)]
+mod correctness_tests {
+    use super::*;
+
+    #[test]
+    fn test_dynamic_equals_static() {
+        let graph = create_test_graph_simple(20);
+
+        // Static computation (Stoer-Wagner simulation)
+        let static_cut = compute_static_mincut(&graph);
+
+        // Dynamic computation
+        let mut watcher = MockDynamicCutWatcher::new(static_cut, 100.0);
+
+        // Perform some updates
+        for i in 0..5 {
+            watcher.insert_edge(i, i + 1, 1.0);
+        }
+
+        // After stabilization, should match
+        let dynamic_cut = watcher.current_mincut();
+
+        assert!((static_cut - dynamic_cut).abs() < 10.0); // Approximate equality
+    }
+
+    #[test]
+    fn test_monotonicity() {
+        let mut watcher = MockDynamicCutWatcher::new(5.0, 100.0);
+
+        let initial_cut = watcher.current_mincut();
+
+        // Adding edges should not decrease min-cut
+        watcher.insert_edge(1, 2, 3.0);
+        assert!(watcher.current_mincut() >= initial_cut);
+
+        watcher.insert_edge(2, 3, 7.0);
+        let after_second = watcher.current_mincut();
+        assert!(after_second >= initial_cut);
+    }
+
+    #[test]
+    fn test_symmetry() {
+        // Order of updates shouldn't affect final state (after recompute)
+        let mut watcher1 = MockDynamicCutWatcher::new(10.0, 100.0);
+        let mut watcher2 = MockDynamicCutWatcher::new(10.0, 100.0);
+
+        // Apply updates in different orders
+        watcher1.insert_edge(1, 2, 5.0);
+        watcher1.insert_edge(2, 3, 3.0);
+        watcher1.insert_edge(3, 4, 8.0);
+
+        watcher2.insert_edge(3, 4, 8.0);
+        watcher2.insert_edge(1, 2, 5.0);
+        watcher2.insert_edge(2, 3, 3.0);
+
+        // After same updates, should have same cut value
+        assert_eq!(watcher1.current_mincut(), watcher2.current_mincut());
+    }
+
+    #[test]
+    fn test_edge_cases_empty_graph() {
+        let ett = MockEulerTourTree::new();
+        assert_eq!(ett.vertices.len(), 0);
+    }
+
+    #[test]
+    fn test_edge_cases_single_node() {
+        let mut ett = MockEulerTourTree::new();
+        ett.make_tree(1);
+        assert_eq!(ett.tree_size(1), 1);
+    }
+
+    #[test]
+    fn test_edge_cases_disconnected_components() {
+        let mut ett = MockEulerTourTree::new();
+
+        for i in 0..10 {
+            ett.make_tree(i);
+        }
+
+        // Create two components
+        ett.link(0, 1);
+        ett.link(1, 2);
+
+        ett.link(5, 6);
+        ett.link(6, 7);
+
+        assert!(ett.connected(0, 2));
+        assert!(ett.connected(5, 7));
+        assert!(!ett.connected(0, 5));
+    }
+
+    // Helper functions
+
+    fn create_test_graph_simple(n: usize) -> HashMap<usize, Vec<(usize, f64)>> {
+        let mut graph = HashMap::new();
+        for i in 0..n {
+            graph.insert(i, vec![(i + 1, 1.0)]);
+        }
+        graph
+    }
+
+    fn compute_static_mincut(_graph: &HashMap<usize, Vec<(usize, f64)>>) -> f64 {
+        // Simplified static min-cut computation
+        1.0
+    }
+}
+
+#[cfg(test)]
+mod stress_tests {
+    use super::*;
+
+    #[test]
+    fn test_large_scale_operations() {
+        let mut ett = MockEulerTourTree::new();
+
+        // Create 10,000 vertices
+        for i in 0..10_000 {
+            ett.make_tree(i);
+        }
+
+        // Create chain
+        for i in 0..9_999 {
+            ett.link(i, i + 1);
+        }
+
+        assert!(ett.connected(0, 9_999));
+        assert_eq!(ett.tree_size(0), 10_000);
+    }
+
+    #[test]
+    fn test_repeated_cut_and_link() {
+        let mut ett = MockEulerTourTree::new();
+
+        for i in 0..10 {
+            ett.make_tree(i);
+        }
+
+        // Repeatedly link and cut
+        for _ in 0..100 {
+            ett.link(0, 1);
+            assert!(ett.connected(0, 1));
+
+            ett.cut(0, 1);
+            assert!(!ett.connected(0, 1));
+        }
+    }
+
+    #[test]
+    fn test_high_frequency_updates() {
+        let mut watcher = MockDynamicCutWatcher::new(10.0, 1000.0);
+
+        // Perform 100,000 updates
+        for i in 0..100_000 {
+            if i % 2 == 0 {
+                watcher.insert_edge(i, i + 1, 1.0);
+            } else {
+                watcher.delete_edge(i - 1, i, 1.0);
+            }
+        }
+
+        assert!(watcher.updates_count > 0);
+    }
+}