Fix clippy findings and related issues

src/testing/graph_topology_addition_testing.rs

@@ -43,10 +43,11 @@ pub fn reserve_vertices_increases_capacity<G: GraphTopologyAddition>() {
 }
 
 pub fn reserve_vertices_prevents_reallocation_on_add<G: GraphTopologyAddition>() {
+    const N: usize = 10;
     let mut graph = G::default();
-    graph.reserve_vertices(10);
+    graph.reserve_vertices(N);
     let capacity_before = graph.vertex_capacity();
-    for _ in 0..10 {
+    for _ in 0..N {
         graph.add_vertex();
     }
     assert_eq!(
@@ -78,12 +79,13 @@ pub fn reserve_edges_increases_capacity<G: GraphTopologyAddition>() {
 }
 
 pub fn reserve_edges_prevents_reallocation_on_add<G: GraphTopologyAddition>() {
+    const N: usize = 10;
     let mut graph = G::default();
     let u = graph.add_vertex();
     let v = graph.add_vertex();
-    graph.reserve_edges(10);
+    graph.reserve_edges(N);
     let capacity_before = graph.edge_capacity();
-    for _ in 0..10 {
+    for _ in 0..N {
         graph.add_edge(u, v);
     }
     assert_eq!(