Add Clone to graph models, and tests

src/testing/graph_topology_addition_clone_testing.rs

@@ -0,0 +1,56 @@
+use crate::testing::fixtures::MakeTestGraph;
+use crate::traits::GraphTopologyAddition;
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! graph_topology_addition_clone_tests {
+    ($T:ty) => {
+        $crate::graph_topology_addition_clone_tests!(@wrap $T,
+            clone_independent,
+        );
+    };
+
+    (@wrap $T:ty, $($name:ident),* $(,)?) => {
+        $(
+            #[test]
+            fn $name() {
+                $crate::testing::graph_topology_addition_clone_testing::$name::<$T>();
+            }
+        )*
+    };
+}
+
+pub fn clone_independent<G: Clone + GraphTopologyAddition>() {
+    let (mut graph, [u, v], _) = G::single_edge();
+    let mut clone = graph.clone();
+
+    let w = clone.add_vertex();
+    clone.add_edge(u, w);
+    assert_eq!(clone.vertex_count(), 3, "precondition: vertex count of clone");
+    assert_eq!(clone.edge_count(), 2, "precondition: edge count of clone");
+    assert_eq!(
+        graph.vertex_count(),
+        2,
+        "mutating the clone should not affect the vertex count of the original"
+    );
+    assert_eq!(
+        graph.edge_count(),
+        1,
+        "mutating the clone should not affect the edge count of the original"
+    );
+
+    let x = graph.add_vertex();
+    graph.add_edge(v, x);
+    assert_eq!(graph.vertex_count(), 3, "precondition: vertex count of original");
+    assert_eq!(graph.edge_count(), 2, "precondition: edge count of original");
+    assert_eq!(
+        clone.vertex_count(),
+        3,
+        "mutating the original should not affect the vertex count of the clone"
+    );
+    assert_eq!(
+        clone.edge_count(),
+        2,
+        "mutating the original should not affect the edge count of the clone"
+    );
+}