Add subscription creation test

tracetools_test/test/test_subscription.cpp

@@ -0,0 +1,41 @@
+#include <memory>
+
+#include "rclcpp/rclcpp.hpp"
+#include "std_msgs/msg/string.hpp"
+
+
+class SubNode : public rclcpp::Node
+{
+public:
+    SubNode(rclcpp::NodeOptions options) : Node("sub_node", options)
+    {
+        sub_ = this->create_subscription<std_msgs::msg::String>(
+            "the_topic",
+            rclcpp::QoS(10),
+            std::bind(&SubNode::callback, this, std::placeholders::_1));
+    }
+
+private:
+    void callback(const std_msgs::msg::String::SharedPtr msg)
+    {
+        // Nothing
+        (void)msg;
+    }
+
+    rclcpp::Subscription<std_msgs::msg::String>::SharedPtr sub_;
+};
+
+int main(int argc, char* argv[])
+{
+    rclcpp::init(argc, argv);
+
+    rclcpp::executors::SingleThreadedExecutor exec;
+    auto sub_node = std::make_shared<SubNode>(rclcpp::NodeOptions());
+    exec.add_node(sub_node);
+
+    printf("spinning once\n");
+    exec.spin_once();
+
+    rclcpp::shutdown();
+    return 0;
+}