diff --git a/src/maps.rs b/src/maps.rs
index 0c123bb..f79d4a8 100644
--- a/src/maps.rs
+++ b/src/maps.rs
@@ -49,115 +49,18 @@ impl<V: Copy, T: Clone> IndexMut<V> for VertexMap<V, T> {
 }
 
 #[cfg(test)]
-mod tests {
+mod append_graph_tests {
     use crate::models::append_graph::AppendGraph;
+    use crate::traits::GraphTopology;
+
+    crate::vertex_map_tests!(AppendGraph);
+}
+
+#[cfg(test)]
+mod graph_tests {
     use crate::models::graph::Graph;
     use crate::traits::{GraphTopology, GraphTopologyDeletion};
 
-    #[test]
-    fn initial_values_are_default() {
-        let mut graph = AppendGraph::new();
-        let v1 = graph.add_vertex();
-        let v2 = graph.add_vertex();
-        let map = graph.vertex_map(42);
-        assert_eq!(map[v1], 42);
-        assert_eq!(map[v2], 42);
-    }
-
-    #[test]
-    fn write_and_read() {
-        let mut graph = AppendGraph::new();
-        let v1 = graph.add_vertex();
-        let v2 = graph.add_vertex();
-        let mut map = graph.vertex_map(0);
-        map[v1] = 7;
-        assert_eq!(map[v1], 7);
-        assert_eq!(map[v2], 0);
-    }
-
-    #[test]
-    fn lazy_growth_on_read() {
-        let mut graph = AppendGraph::new();
-        graph.add_vertex();
-        let map = graph.vertex_map(99);
-        let v = graph.add_vertex();
-        assert_eq!(map[v], 99);
-    }
-
-    #[test]
-    fn lazy_growth_on_write() {
-        let mut graph = AppendGraph::new();
-        let v1 = graph.add_vertex();
-        let mut map = graph.vertex_map(0);
-        let v2 = graph.add_vertex();
-        map[v2] = 7;
-        assert_eq!(map[v1], 0);
-        assert_eq!(map[v2], 7);
-    }
-
-    #[test]
-    fn sync_expands_to_new_vertices() {
-        let mut graph = AppendGraph::new();
-        graph.add_vertex();
-        let mut map = graph.vertex_map(42);
-        graph.add_vertex();
-        graph.add_vertex();
-        assert!(
-            map.data.len() < graph.vertex_capacity(),
-            "precondition: map is stale before sync"
-        );
-        map.sync(&graph);
-        assert_eq!(map.data.len(), graph.vertex_capacity());
-    }
-
-    #[test]
-    fn sync_does_not_overwrite_existing_values() {
-        let mut graph = AppendGraph::new();
-        let v = graph.add_vertex();
-        let mut map = graph.vertex_map(0);
-        map[v] = 5;
-        graph.add_vertex();
-        map.sync(&graph);
-        assert_eq!(map[v], 5);
-    }
-
-    #[test]
-    fn surviving_vertex_readable_after_delete() {
-        let mut graph = Graph::new();
-        let v1 = graph.add_vertex();
-        let v2 = graph.add_vertex();
-        let mut map = graph.vertex_map(0);
-        map[v1] = 1;
-        map[v2] = 2;
-        graph.delete_vertex(v2);
-        assert_eq!(map[v1], 1);
-    }
-
-    #[test]
-    fn capacity_does_not_shrink_after_delete() {
-        let mut graph = Graph::new();
-        let v1 = graph.add_vertex();
-        let v2 = graph.add_vertex();
-        let mut map = graph.vertex_map(0);
-        let capacity_before = graph.vertex_capacity();
-        graph.delete_vertex(v2);
-        map.sync(&graph);
-        assert_eq!(map.data.len(), capacity_before);
-        assert_eq!(map[v1], 0);
-    }
-
-    #[test]
-    fn reused_slot_returns_old_value() {
-        let mut graph = Graph::new();
-        graph.add_vertex();
-        let v1 = graph.add_vertex();
-        let mut map = graph.vertex_map(0);
-        map[v1] = 99;
-        graph.delete_vertex(v1);
-        let v2 = graph.add_vertex();
-        // VertexMap uses raw indices, not vertex identity. A new vertex v2 reusing the slot of
-        // previously deleted vertex v1 sees the old value. Callers must reinitialize stale
-        // slots after deletion.
-        assert_eq!(map[v2], 99);
-    }
+    crate::vertex_map_tests!(Graph);
+    crate::vertex_map_deletion_tests!(Graph);
 }
diff --git a/src/testing.rs b/src/testing.rs
index ecf3963..7975b1f 100644
--- a/src/testing.rs
+++ b/src/testing.rs
@@ -1 +1,2 @@
 pub(crate) mod graph_topology_testing;
+pub(crate) mod vertex_map_testing;
diff --git a/src/testing/vertex_map_testing.rs b/src/testing/vertex_map_testing.rs
new file mode 100644
index 0000000..e97df88
--- /dev/null
+++ b/src/testing/vertex_map_testing.rs
@@ -0,0 +1,120 @@
+#[cfg(test)]
+#[macro_export]
+macro_rules! vertex_map_tests {
+    ($T:ty) => {
+        #[test]
+        fn initial_values_are_default() {
+            let mut graph = <$T>::new();
+            let v1 = graph.add_vertex();
+            let v2 = graph.add_vertex();
+            let map = graph.vertex_map(42);
+            assert_eq!(map[v1], 42);
+            assert_eq!(map[v2], 42);
+        }
+
+        #[test]
+        fn write_and_read() {
+            let mut graph = <$T>::new();
+            let v1 = graph.add_vertex();
+            let v2 = graph.add_vertex();
+            let mut map = graph.vertex_map(0);
+            map[v1] = 7;
+            assert_eq!(map[v1], 7);
+            assert_eq!(map[v2], 0);
+        }
+
+        #[test]
+        fn lazy_growth_on_read() {
+            let mut graph = <$T>::new();
+            graph.add_vertex();
+            let map = graph.vertex_map(99);
+            let v = graph.add_vertex();
+            assert_eq!(map[v], 99);
+        }
+
+        #[test]
+        fn lazy_growth_on_write() {
+            let mut graph = <$T>::new();
+            let v1 = graph.add_vertex();
+            let mut map = graph.vertex_map(0);
+            let v2 = graph.add_vertex();
+            map[v2] = 7;
+            assert_eq!(map[v1], 0);
+            assert_eq!(map[v2], 7);
+        }
+
+        #[test]
+        fn sync_expands_to_new_vertices() {
+            let mut graph = <$T>::new();
+            graph.add_vertex();
+            let mut map = graph.vertex_map(42);
+            let initial_len = map.data.len();
+            while graph.vertex_capacity() <= initial_len {
+                graph.add_vertex();
+            }
+            assert!(
+                map.data.len() < graph.vertex_capacity(),
+                "precondition: map is stale before sync"
+            );
+            map.sync(&graph);
+            assert_eq!(map.data.len(), graph.vertex_capacity());
+        }
+
+        #[test]
+        fn sync_does_not_overwrite_existing_values() {
+            let mut graph = <$T>::new();
+            let v = graph.add_vertex();
+            let mut map = graph.vertex_map(0);
+            map[v] = 5;
+            graph.add_vertex();
+            map.sync(&graph);
+            assert_eq!(map[v], 5);
+        }
+    };
+}
+
+#[cfg(test)]
+#[macro_export]
+macro_rules! vertex_map_deletion_tests {
+    ($T:ty) => {
+        #[test]
+        fn surviving_vertex_readable_after_delete() {
+            let mut graph = <$T>::new();
+            let v1 = graph.add_vertex();
+            let v2 = graph.add_vertex();
+            let mut map = graph.vertex_map(0);
+            map[v1] = 1;
+            map[v2] = 2;
+            graph.delete_vertex(v2);
+            assert_eq!(map[v1], 1);
+        }
+
+        #[test]
+        fn capacity_does_not_shrink_after_delete() {
+            let mut graph = <$T>::new();
+            let v1 = graph.add_vertex();
+            let v2 = graph.add_vertex();
+            let mut map = graph.vertex_map(0);
+            let capacity_before = graph.vertex_capacity();
+            graph.delete_vertex(v2);
+            map.sync(&graph);
+            assert_eq!(map.data.len(), capacity_before);
+            assert_eq!(map[v1], 0);
+        }
+
+        #[test]
+        fn reused_slot_returns_old_value() {
+            let mut graph = <$T>::new();
+            graph.add_vertex();
+            let v1 = graph.add_vertex();
+            let mut map = graph.vertex_map(0);
+            map[v1] = 99;
+            graph.delete_vertex(v1);
+            let v2 = graph.add_vertex();
+            // VertexMap uses raw indices, not vertex identity. A new vertex v2 reusing the slot
+            // of previously deleted v1 sees the old value. Callers must reinitialize stale slots
+            // after deletion.
+            assert_eq!(map[v2], 99);
+        }
+    };
+}