Add test for GraphTopology::vertices() after delete

src/testing/graph_topology_testing.rs

@@ -553,5 +553,35 @@ macro_rules! graph_topology_deletion_tests {
             let result = std::panic::catch_unwind(move || graph.delete_edge(e));
             assert!(result.is_err(), "second deletion should panic");
         }
+
+        #[test]
+        fn vertices_after_delete() {
+            let (mut graph, vertices) = make_test_graph();
+            graph.delete_vertex(vertices[2]);
+            assert_eq!(
+                graph.vertex_count(),
+                9,
+                "unexpected vertex count after delete"
+            );
+            assert_eq!(
+                graph.vertices().count(),
+                9,
+                "unexpected vertex iterator count after delete"
+            );
+            for v in graph.vertices() {
+                assert_ne!(
+                    v, vertices[2],
+                    "deleted vertex {:?} appeared in iterator",
+                    vertices[2]
+                );
+            }
+            for i in [0, 1, 3, 4, 5, 6, 7, 8, 9] {
+                assert!(
+                    graph.vertices().any(|v| v == vertices[i]),
+                    "expected vertex {:?} missing from iterator after delete",
+                    vertices[i]
+                );
+            }
+        }
     };
 }