Fix clippy findings and related issues

src/testing/fixtures.rs

@@ -5,6 +5,8 @@ use crate::models::{AppendGraph, FrozenGraph};
 use crate::traits::{GraphTopology, GraphTopologyAddition, GraphTopologyConversion, Incidence};
 
 pub trait MakeTestGraph: GraphTopology + Sized {
+    // Since this is only a test fixture, the complex return type here is deemed acceptable.
+    #[allow(clippy::type_complexity)]
     fn standard() -> (
         Self,
         [Self::Vertex; 10],
@@ -293,12 +295,12 @@ pub fn assert_standard_unweighted_predecessors_v0<V: Debug + Copy + PartialEq>(
         vec![Some(vertices[4])],
         vec![Some(vertices[5]), Some(vertices[6]), Some(vertices[7])],
     ];
-    for i in 0..10 {
+    assert_eq!(vertices.len(), expected.len());
+    for (&v, exp) in vertices.iter().zip(&expected) {
         assert!(
-            expected[i].contains(&actual[vertices[i]]),
-            "unexpected predecessor {:?} of vertex {:?}",
-            actual[vertices[i]],
-            vertices[i]
+            exp.contains(&actual[v]),
+            "unexpected predecessor {:?} of vertex {v:?}",
+            actual[v]
         );
     }
 }
@@ -320,8 +322,7 @@ where
 {
     let path = path_option.unwrap_or_else(|| {
         panic!(
-            "path should exist between source vertex {:?} and connected targets {:?}",
-            source, targets
+            "path should exist between source vertex {source:?} and connected targets {targets:?}"
         )
     });