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Writing Basic Tests with Python
Starting point: we’ll assume you have a basic ament_python package set up already and you want to add some tests to it.
If you are using ament_cmake_python, refer to the the ament_cmake_python docs for how to make tests dicoverable.
The test contents and invocation with
colcon remain the same.
setup.py must a test dependency on
pytest within the call to
Test Files and Folders
Your test code needs to go in a folder named
tests in the root of your package.
Any file that contains tests that you want to run must have the pattern
FOO can be replaced with anything.
Example package layout:
You can now write tests to your heart’s content. There are plenty of resources on pytest, but in short, you can write functions with the
test_ prefix and include whatever assert statements you’d like.
assert 2 + 2 == 5 # This should fail for most mathematical systems
See the tutorial on how to run tests from the command line for more information on running the tests and inspecting the test results.
Beyond the standard colcon testing commands you can also specify arguments to the
pytest framework from the command line with the
For example, you can specify the name of the function to run with
colcon test --packages-select <name-of-pkg> --pytest-args -k name_of_the_test_function
To see the pytest output while running the tests, use these flags:
colcon test --event-handlers console_cohesion+