Refactor graph trait tests to minimize macro code, and split into separate files per macro

The tests only declare a list of tests in the macro, no longer the test functions themselves. This allows better tooling support (e.g. IDE and rustfmt).

src/testing/graph_topology_addition_deletion_testing.rs

@@ -0,0 +1,62 @@
+use std::fmt::Debug;
+
+use crate::testing::fixtures::MakeTestGraph;
+use crate::traits::{GraphTopologyAddition, GraphTopologyDeletion};
+
+#[doc(hidden)]
+#[macro_export]
+macro_rules! graph_topology_addition_deletion_tests {
+    ($T:ty) => {
+        $crate::graph_topology_addition_deletion_tests!(@wrap $T,
+            delete_vertex_add_vertex,
+            delete_edge_add_edge,
+        );
+    };
+
+    (@wrap $T:ty, $($name:ident),* $(,)?) => {
+        $(
+            #[test]
+            fn $name() {
+                $crate::testing::graph_topology_addition_deletion_testing::$name::<$T>();
+            }
+        )*
+    };
+}
+
+pub(crate) fn delete_vertex_add_vertex<G: GraphTopologyDeletion + GraphTopologyAddition>()
+where
+    G::Vertex: Debug,
+{
+    let (mut graph, v) = G::single_vertex();
+    graph.delete_vertex(v);
+    assert_eq!(
+        graph.vertex_count(),
+        0,
+        "unexpected vertex count after delete"
+    );
+    assert_ne!(
+        graph.add_vertex(),
+        v,
+        "unexpected duplicate vertex after delete"
+    );
+    assert_eq!(
+        graph.vertex_count(),
+        1,
+        "unexpected vertex count after re-add"
+    );
+}
+
+pub(crate) fn delete_edge_add_edge<G: GraphTopologyDeletion + GraphTopologyAddition>()
+where
+    G::Edge: Debug,
+{
+    let (mut graph, vertices, e) = G::single_edge();
+    graph.delete_edge(e);
+    assert_eq!(graph.edge_count(), 0, "unexpected edge count after delete");
+    assert_ne!(
+        graph.add_edge(vertices[0], vertices[1]),
+        e,
+        "unexpected duplicate edge after re-add"
+    );
+    assert_eq!(graph.edge_count(), 1, "unexpected edge count after re-add");
+}