What is the best way to test a ROS node in isolation?

1 What is rostest?

Rostest is a tool that integrates the roslaunch and roscpp_test frameworks to enable unit testing of ROS nodes. Rostest allows you to launch one or more nodes in a test environment, and to write test cases using C++ or Python. You can use rostest to test individual nodes or groups of nodes, and to measure their performance, resource usage, and communication. Rostest can also generate XML reports that can be used by other tools such as Jenkins or ROS Dashboard.

2 How to write a rostest file?

A rostest file is a launch file that specifies the nodes to be tested, the test cases to be executed, and the parameters and arguments to be passed. A rostest file has the same syntax as a roslaunch file, except that it uses the <test> tag instead of the <node> tag for the nodes that are being tested. The <test> tag has some additional attributes, such as test-name, pkg, type, and time-limit, that define the name, package, executable, and timeout of the test node. You can also use the <param> and <arg> tags to set parameters and arguments for the test node.

3 How to write a test case?

A test case is a C++ or Python script that implements the logic of the test. A test case can use the roscpp or rospy libraries to interact with the ROS system, such as creating publishers, subscribers, services, or actions. A test case can also use the gtest or unittest modules to define assertions and expectations, such as checking the values of topics, messages, or parameters. A test case can have multiple test methods, each of which should have a descriptive name and perform a specific task. A test case should also have a main function that initializes the ROS node and runs the tests.

4 How to use mocks and stubs?

Mocks and stubs are techniques to simulate the behavior and data of other nodes or components that are not part of the test. Mocks and stubs can help you isolate your node from external dependencies and test its functionality in different scenarios. You can use mocks and stubs to create fake publishers, subscribers, services, or actions that send or receive predefined messages or responses. You can also use mocks and stubs to manipulate parameters or environment variables that affect your node. You can implement mocks and stubs using the rosmock or rosstubs libraries, or using your own custom code.

5 How to run a rostest?

To run a rostest, you need to compile your test nodes and test cases using catkin_make or catkin build, and then use the rostest command with the name of the rostest file as an argument. For example, rostest my_pkg my_test.launch. You can also use the --text option to see the output of the test nodes and test cases, or the --results option to see the XML reports. You can also use the --reuse-master option to reuse an existing roscore, or the --clear option to delete the previous test results.

6 How to debug a rostest?

Debugging a rostest can be challenging, as you may need to inspect multiple nodes, processes, and files. However, there are some tools and techniques that can help you find and fix errors in your tests. You can use the rostopic, rosservice, rosparam, or rosnode commands to monitor the topics, services, parameters, and nodes in your test environment. You can also use the rosout or rqt_console tools to see the log messages from your nodes and test cases. You can also use the gdb or pdb tools to attach to your test nodes or test cases and set breakpoints, watchpoints, or commands.

7 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?