Add loops and multi-edges to the test graph, fix neighbors() test

src/models/graph.rs

@@ -267,5 +267,4 @@ mod tests {
         graph.delete_edge(f);
         assert_eq!(graph.edge_count(), 0, "unexpected edge count after delete");
     }
-
 }

src/testing/graph_topology_testing.rs

@@ -7,13 +7,17 @@ macro_rules! graph_topology_test_fixtures {
             let vertices: [<$T as $crate::traits::GraphTopology>::Vertex; 10] =
                 core::array::from_fn(|_| graph.add_vertex());
             graph.add_edge(vertices[0], vertices[1]);
+            graph.add_edge(vertices[0], vertices[1]);
             graph.add_edge(vertices[1], vertices[2]);
             graph.add_edge(vertices[1], vertices[3]);
             graph.add_edge(vertices[1], vertices[4]);
+            graph.add_edge(vertices[2], vertices[2]);
+            graph.add_edge(vertices[2], vertices[4]);
             graph.add_edge(vertices[2], vertices[4]);
             graph.add_edge(vertices[2], vertices[5]);
             graph.add_edge(vertices[2], vertices[6]);
             graph.add_edge(vertices[3], vertices[6]);
+            graph.add_edge(vertices[4], vertices[4]);
             graph.add_edge(vertices[4], vertices[7]);
             graph.add_edge(vertices[4], vertices[8]);
             graph.add_edge(vertices[5], vertices[9]);
@@ -66,7 +70,7 @@ macro_rules! graph_topology_tests {
         #[test]
         fn edge_count() {
             let (graph, _) = make_test_graph();
-            assert_eq!(graph.edge_count(), 14, "unexpected edge count");
+            assert_eq!(graph.edge_count(), 18, "unexpected edge count");
         }
 
         #[test]
@@ -79,7 +83,7 @@ macro_rules! graph_topology_tests {
         #[test]
         fn degree() {
             let (graph, vertices) = make_test_graph();
-            let expected_degrees = [1, 4, 4, 2, 4, 2, 3, 3, 2, 3];
+            let expected_degrees = [2, 5, 7, 2, 7, 2, 3, 3, 2, 3];
             for i in 0..graph.vertex_count() {
                 assert_eq!(
                     graph.degree(vertices[i]),
@@ -136,8 +140,7 @@ macro_rules! graph_topology_tests {
 
             for i in 0..graph.vertex_count() {
                 let exp = match i {
-                    2 => continue,
-                    1 | 4 | 5 | 6 => true,
+                    1 | 2 | 4 | 5 | 6 => true,
                     _ => false,
                 };
                 assert_eq!(
@@ -199,20 +202,35 @@ macro_rules! graph_topology_tests {
             // Checks neighbors of vertex 4.
             assert_eq!(
                 graph.neighbors(vertices[4]).count(),
-                4,
+                7,
                 "unexpected neighbor count"
             );
-
-            // Expects each neighbor to appear exactly once. This will not work if there are multiple edges.
-            let neighbors = vec![vertices[1], vertices[2], vertices[7], vertices[8]];
+            let mut expected_neighbors = vec![
+                vertices[1],
+                vertices[2],
+                vertices[2],
+                vertices[4],
+                vertices[4],
+                vertices[7],
+                vertices[8],
+            ];
             for v in graph.neighbors(vertices[4]) {
-                assert_eq!(
-                    neighbors.iter().filter(|&x| *x == v).count(),
-                    1,
-                    "unexpected neighbor {v:?} of {:?} from the iterator",
-                    vertices[4]
-                );
+                let i = expected_neighbors
+                    .iter()
+                    .position(|w| *w == v)
+                    .expect(&format!(
+                        "unexpected neighbor {v:?} of {:?} from the iterator",
+                        vertices[4]
+                    ));
+                expected_neighbors.swap_remove(i);
             }
+            assert_eq!(
+                expected_neighbors.len(),
+                0,
+                "expected neighbors {:?} of {:?} were not matched by the iterator",
+                expected_neighbors,
+                vertices[4]
+            );
         }
 
         #[test]
@@ -359,7 +377,7 @@ macro_rules! graph_topology_deletion_tests {
             );
             assert_eq!(
                 graph.edge_count(),
-                14,
+                18,
                 "unexpected edge count before delete"
             );
             graph.delete_vertex(vertices[2]);
@@ -368,12 +386,13 @@ macro_rules! graph_topology_deletion_tests {
                 9,
                 "unexpected vertex count after delete"
             );
-            assert_eq!(graph.edge_count(), 10, "unexpected edge count after delete");
+            assert_eq!(graph.edge_count(), 12, "unexpected edge count after delete");
             let expected_edges = [
                 (vertices[0], vertices[1]),
                 (vertices[1], vertices[3]),
                 (vertices[1], vertices[4]),
                 (vertices[3], vertices[6]),
+                (vertices[4], vertices[4]),
                 (vertices[4], vertices[7]),
                 (vertices[4], vertices[8]),
                 (vertices[5], vertices[9]),