Fix unit test and break out magic constants into named values

Signed-off-by: Emerson Knapp <emerson.b.knapp@gmail.com>

Author: emersonknapp

nav2_route/include/nav2_route/utils.hpp

@@ -82,9 +82,10 @@ inline visualization_msgs::msg::MarkerArray toMsg(
   edges_marker.scale.x = 0.1;  // Line width
   edges_marker.color.g = 1.0;
   edges_marker.color.a = 0.5;  // Semi-transparent green so bidirectional connections stand out
-  // Each edge has 2 points, each node is likely to have at least 2 edges.
-  // This likely under-reserves but saves some initial reallocations
-  edges_marker.points.reserve(graph.size() * 2 * 2);
+  constexpr size_t points_per_edge = 2;
+  // This probably under-reserves but saves some initial reallocations
+  constexpr size_t likely_min_edges_per_node = 2;
+  edges_marker.points.reserve(graph.size() * points_per_edge * likely_min_edges_per_node);
 
   geometry_msgs::msg::Point node_pos;
   geometry_msgs::msg::Point edge_start;

nav2_route/test/test_utils_and_types.cpp

@@ -159,7 +159,15 @@ TEST(UtilsTest, test_to_visualization_msg_conversion)
   graph[3].addEdge(default_cost, &graph[6], ids++);
 
   auto graph_msg = utils::toMsg(graph, frame, time);
-  EXPECT_EQ(graph_msg.markers.size(), 34u);  // 9 nodes and 8 edges (with text markers)
+  constexpr size_t expected_edge_markers = 1;
+  constexpr size_t expected_node_markers = 1;
+  constexpr size_t expected_edge_id_text_markers = 8;
+  constexpr size_t expected_node_id_text_markers = 9;
+  constexpr size_t expected_total_markers =
+    expected_edge_markers + expected_node_markers +
+    expected_edge_id_text_markers + expected_node_id_text_markers;
+
+  EXPECT_EQ(graph_msg.markers.size(), expected_total_markers);
   for (auto & marker : graph_msg.markers) {
     if (marker.ns == "route_graph_ids") {
       EXPECT_EQ(marker.type, visualization_msgs::msg::Marker::TEXT_VIEW_FACING);