Improved test coverage

Signed-off-by: Marvin Hansen <[email protected]>

Author: marvin-hansen

ultragraph/src/types/storage/graph_csm/graph_csm_algo_topological.rs

@@ -134,7 +134,7 @@ where
     fn topological_sort(&self) -> Result<Option<Vec<usize>>, GraphError> {
         let num_nodes = self.number_nodes();
         if num_nodes == 0 {
-            return Ok(Some(Vec::new()));
+            return Ok(None);
         }
 
         // 1. Compute in-degrees for all nodes.

ultragraph/tests/types/ultra_graph/graph_algo_centrality_tests.rs

@@ -98,6 +98,38 @@ fn test_betweenness_centrality_normalized() {
     });
 }
 
+#[test]
+fn test_betweenness_centrality_directed_normalized() {
+    let mut g = UltraGraphWeighted::<i32, i32>::new();
+    g.add_node(0).unwrap();
+    g.add_node(1).unwrap();
+    g.add_node(2).unwrap();
+    g.add_node(3).unwrap();
+
+    // 0 -> 1 -> 2
+    // 0 -> 3 -> 2
+    g.add_edge(0, 1, 1).unwrap();
+    g.add_edge(1, 2, 1).unwrap();
+    g.add_edge(0, 3, 1).unwrap();
+    g.add_edge(3, 2, 1).unwrap();
+    g.freeze();
+
+    // N = 4
+    // Directed normalization factor: (N-1)(N-2) = (3)(2) = 6
+    // Unnormalized BC(1) = 0.5, BC(3) = 0.5
+    // Normalized BC(1) = 0.5 / 6.0 = 0.0833...
+    // Normalized BC(3) = 0.5 / 6.0 = 0.0833...
+    let result = g.betweenness_centrality(true, true).unwrap();
+    let expected = [(0, 0.0), (1, 0.5 / 6.0), (2, 0.0), (3, 0.5 / 6.0)];
+    result.iter().for_each(|(node, score)| {
+        let expected_score = expected.iter().find(|(n, _)| n == node).unwrap().1;
+        assert!(
+            (score - expected_score).abs() < 1e-9,
+            "Node {node}: Expected {expected_score}, Got {score}"
+        );
+    });
+}
+
 #[test]
 fn test_pathway_betweenness_centrality_undirected() {
     let mut g = UltraGraphWeighted::<i32, i32>::new();

ultragraph/tests/types/ultra_graph/graph_algo_pathfinder_tests.rs

@@ -46,6 +46,15 @@ fn test_shortest_path_len_on_static_graph() {
     assert_eq!(g.shortest_path_len(3, 0).unwrap(), None);
 }
 
+#[test]
+fn test_shortest_path_len_is_one() {
+    let g = utils_tests::get_acyclic_graph();
+    let res = g.shortest_path_len(0, 0);
+    assert!(res.is_ok());
+    let res = res.unwrap();
+    assert_eq!(res, Some(1));
+}
+
 #[test]
 fn test_shortest_path_on_dynamic_graph() {
     let mut g = UltraGraph::new();
@@ -57,6 +66,18 @@ fn test_shortest_path_on_dynamic_graph() {
     ));
 }
 
+#[test]
+fn test_shortest_path_is_one() {
+    let mut g = UltraGraph::new();
+    g.add_node(0).unwrap();
+    g.freeze();
+
+    let res = g.shortest_path(0, 0);
+    assert!(res.is_ok());
+    let res = res.unwrap();
+    assert_eq!(res, Some(vec![0]));
+}
+
 #[test]
 fn test_shortest_path_on_static_graph() {
     let g = utils_tests::get_acyclic_graph();

ultragraph/tests/types/ultra_graph/graph_csm_algo_topological_tests.rs

@@ -3,7 +3,9 @@
  * Copyright (c) "2025" . The DeepCausality Authors and Contributors. All Rights Reserved.
  */
 use ultragraph::utils::utils_tests;
-use ultragraph::{GraphError, GraphMut, GraphView, TopologicalGraphAlgorithms, UltraGraph};
+use ultragraph::{
+    GraphError, GraphMut, GraphView, TopologicalGraphAlgorithms, UltraGraph, UltraGraphContainer,
+};
 
 #[test]
 fn test_find_cycle_on_dynamic_graph() {
@@ -12,6 +14,13 @@ fn test_find_cycle_on_dynamic_graph() {
     assert!(matches!(g.find_cycle(), Err(GraphError::GraphNotFrozen)));
 }
 
+#[test]
+fn test_find_cycle_on_empty_graph() {
+    let mut g: UltraGraphContainer<u64, ()> = UltraGraph::new();
+    g.freeze();
+    assert!(matches!(g.find_cycle(), Ok(None)));
+}
+
 #[test]
 fn test_find_cycle_on_cyclic_graph() {
     let g = utils_tests::get_cyclic_graph();
@@ -71,3 +80,10 @@ fn test_topological_sort_on_acyclic_graph() {
     let sorted = g.topological_sort().unwrap().unwrap();
     assert_eq!(sorted, vec![0, 1, 2, 3]);
 }
+
+#[test]
+fn test_topological_sort_on_empty_graph() {
+    let mut g: UltraGraphContainer<u64, ()> = UltraGraph::new();
+    g.freeze();
+    assert!(matches!(g.topological_sort(), Ok(None)));
+}