ROS2 Automated Unit Test: Node Health Checker

Problem Statement

Implement a test harness that verifies a heartbeat publisher node is working correctly.

You are given a simple heartbeat node (provided in the extra file heartbeat_node.py). Write a function test_heartbeat_node() that:

Requirements

Your function must:

1. Initialize rclpy (rclpy.init())
2. Create a HeartbeatNode instance (import from heartbeat_node)
3. Create a subscriber node that listens on /heartbeat (std_msgs/String)
4. Spin both nodes for 3 seconds to collect messages
5. Assert that at least 2 messages were received
6. Assert that every received message's .data field contains the string 'alive'
7. Return True if all assertions pass, False otherwise
8. Always call rclpy.shutdown() in a finally block

The function must not raise exceptions — catch any assertion failures and return False.

🤖 Why This Matters in Real Robots

Node-level tests catch regressions before they reach hardware. If your heartbeat node stops publishing, a test like this fails in CI within seconds — not when a robot crashes in the field 3 weeks later. Every ROS2 production codebase at Boston Dynamics, Clearpath, and PAL Robotics has hundreds of these.