How do you test ROS nodes in Python?

1 What is rostest?

Rostest is a command-line tool that allows you to run integration tests for ROS nodes. It is based on the roslaunch tool, which is used to start multiple nodes and configure their parameters and connections. Rostest can launch nodes, run tests, and collect results in XML format. You can use rostest to test nodes individually or as part of a system. To use rostest, you need to create a launch file that specifies the nodes and tests to run, and then execute it with the rostest command.

2 How to write tests with unittest?

Unittest is a standard Python module that provides a framework for writing and running unit tests. Unit tests are designed to check the functionality of a single component or function in isolation. Unittest provides a set of classes and methods to create test cases, assert conditions, and report results. You can use unittest to write tests for ROS nodes in Python, as long as you import the rospy module and initialize the node in the setUp method of the test class. You can also use unittest to mock ROS services, topics, and parameters with the rospytest module.

3 How to write tests with rospy?

Rospy is the Python client library for ROS. It provides a set of functions and classes to interact with ROS nodes, topics, services, parameters, and time. Rospy also offers some features for testing ROS nodes in Python, such as the rospy.init_node function, which allows you to specify a name and an anonymous flag for the test node. This ensures that the test node has a unique name and does not interfere with other nodes. Rospy also provides the rospy.is_shutdown function, which returns True if the test node is requested to shut down by ROS. This can be used to terminate the test loop gracefully.

4 How to run tests with rostest?

To run tests with rostest, you need to create a launch file that specifies the nodes and tests to run. The launch file should have the .test extension and use the <test> tag to define the test nodes. The <test> tag has several attributes, such as name, pkg, type, and test-name, that identify the test node and its parameters. The launch file can also use the <node> tag to launch other nodes that are needed for the test scenario. To execute the launch file, you need to run the rostest command with the name of the launch file as an argument.

5 How to analyze test results?

Rostest generates test results in XML format and stores them in the ~/.ros/test_results directory by default. You can view the test results with the rostest-results command, which prints a summary of the test outcomes and errors. You can also use the rostest --text option to display the test results in plain text format. Alternatively, you can use the rostest --results-filename option to specify a different location for the test results file. You can then use any XML parser or tool to analyze the test results in more detail.

6 Here’s what else to consider

This is a space to share examples, stories, or insights that don’t fit into any of the previous sections. What else would you like to add?