Closes #28

tests/tree_node_test.cpp

@@ -16,7 +16,7 @@ int main() {
     frame.signals.push_back(signal);
     database.frames.push_back(frame);
     database.frames.push_back(frame);
-    auto root = DbcTreeBuilder().Build(database);
+    std::unique_ptr<TreeNode> root = DbcTreeBuilder().Build(database);
     Check(root->GetParent() == nullptr && root->GetRow() == 0);
     root->AddChild(nullptr);
     Check(root->GetChildCount() == 2 && !root->GetChild(2));
@@ -28,6 +28,6 @@ int main() {
             Check(leaf->GetParent() == child && leaf->GetRow() == position);
         }
     }
-    auto transferred = std::move(root);
+    std::unique_ptr<TreeNode> transferred = std::move(root);
     Check(transferred->GetChild(0)->GetParent() == transferred.get());
 }