ROS 2 TDD Workflow

Core Principles

1. •Tests FIRST: Write gtest or pytest before implementation.
2. •Red-Green-Refactor: Test fail -> Code fix -> Optimize.
3. •Integration: Use launch_testing for node interaction tests.

Workflow

1. Define Requirements (User Story)

"As a robot, I need to stop when obstacle < 0.5m."

2. Write Test Case

C++ (GTest)

TEST_F(SafetyNodeTest, StopsOnObstacle) {
  node_->publish_scan(0.4); // Simulate 0.4m
  auto cmd = node_->get_cmd_vel();
  EXPECT_EQ(cmd.linear.x, 0.0);
}

Python (Pytest)

def test_stop_on_obstacle(safety_node):
    safety_node.publish_scan(0.4)
    cmd = safety_node.get_cmd_vel()
    assert cmd.linear.x == 0.0

3. Run Test (Fail)

colcon test --packages-select my_safety_pkg

4. Implement Logic

Write minimal code in safety_node to pass the test.

5. Verify & Coverage

colcon test --packages-select my_safety_pkg
colcon test-result --all

Tools

• •Unit: ament_cmake_gtest, ament_cmake_pytest
• •Integration: launch_testing, osrf_pycommon
• •Mocking: gmock (C++), unittest.mock (Python)