[ROS2] Testing launch of Node

edit

I've been trying to write some tests for my package, but with not much success until now...

I have a "PelicanUnit" node and in its constructor I require a path to a .sdf model: if that's not given, everything shuts down with a std::runtime_error. Now, using colcon test and Google Test, I've been trying to write sort of like smoketests for successful and unsuccessful launches. The failing case has been a little tricky, but in the end I've managed with this:

TEST(SmokeTests, ParseModelFailing) {
     // Initialize RCLCPP
     rclcpp::init(0, nullptr);
     EXPECT_THROW(
         {
             try {
                 PelicanUnit pelican;
             } catch (const std::exception& e) {
                 EXPECT_STREQ("Agent model could not be parsed!", e.what());
                 throw; // Re-throw the exception for Google Test to catch
             }
         }, 
         std::runtime_error);
     // Shutdown RCLCPP
     rclcpp::shutdown(); 
}

Unfortunately, I cannot find a way for the other test.

Up until now I've tried:

• launching the node from the test itself but I could not pass the config file I normally use with the standard launch file

  TEST(SmokeTests, Main) {
      // Useless, since the node itself does not parse arguments (?)
      char  arg0[] = "--params-file";
      char  arg1[] = "src/pelican/config/copter1.yaml"; // TODO: use package share directory
      char* argv[] = { &arg0[0], &arg1[0], NULL };
      int   argc   = (int)(sizeof(argv) / sizeof(argv[0])) - 1;
  
      // Initialization
      rclcpp::init(argc, argv);
  
      // Instantiation
      rclcpp::Node::SharedPtr node = std::make_shared<PelicanUnit>();
      rclcpp::executors::MultiThreadedExecutor executor;
  
      executor.add_node(node);
      executor.spin();
  
      rclcpp::shutdown();
  }
  

• using a test launch_file, which has been somewhat almost good, but the config file used has not been found and, most importantly, I'm not sure I can use this as a proper test. I can only test that the command is launched, not that the node itself fires up smoothly...

  TEST(SmokeTests, NodeStartingCorrectly) {
      // Set the launch file path and arguments
      const std::string pwd = "source ";
      const std::string launch_command = "ros2 launch pelican test_launch.launch.py";
  
      // Run the launch command and check its exit status
      std::system(pwd.c_str());
      int exit_status = std::system(launch_command.c_str());
      ASSERT_EQ(exit_status, 0);
  }
  

(launch file)

from launch import LaunchDescription
from launch.actions import DeclareLaunchArgument
from launch_ros.actions import Node
from launch_ros.substitutions import FindPackageShare
from launch.substitutions import PathJoinSubstitution, ThisLaunchFileDir


def generate_launch_description():
    config_pkg_share = FindPackageShare('pelican')
    config_middleware = 'config/'

    ld =  LaunchDescription()

    config_file = 'copter1.yaml'

    node = Node(
            package='pelican',
            executable='pelican_unit',
            ros_arguments=['--params-file', 
                           PathJoinSubstitution([config_pkg_share, config_middleware, config_file])]
        )

    ld.add_action(node)

    return ld

Is there anyone that can provide some assistance or suggestions for this? Thank you!