Testing

Testing#

Automatic code testing is absolutely essential for the development of simtools. It ensures that the code is working as expected and that new features do not break existing functionality.

Important

Developers should expect that code changes affecting several modules are acceptable in case unit tests are successful.

The testing should be done at two levels:

  • unit tests: test individual modules and functions

  • integration tests: test applications as a whole using typical use cases

The pytest framework is used for testing. The test modules are located in simtools/tests separated by unit and integration tests.

Important

The rule should be that any discovered bug or issue should trigger the implementation of tests which reproduce the issue and prevent it from reoccurring.

Pytest fixtures#

General service functions for tests (e.g., DB connection) are defined as pytest.fixtures in conftest.py. This should be used to avoid duplication.

Define fixtures as local as possible: fixtures which are used in a single test module should be defined at the top of the the same module.

All fixtures can be listed with:

pytest --fixtures

Fixtures should therefore include a docstring.

Unit tests#

Unit tests should be written for every module and function and should test the result of individual functions (“units”). It is recommended to write unit tests in parallel with the modules to assure that the code is testable.

Warning

The simtools project aims for a high test coverage. Code lines without coverage should be the exception and the aim should be to achieve a coverage greater than 90% (the CTAO quality requirements aim for a coverage of at least 80%).

Check the test coverage with pytest -n auto --cov-report-html  tests/unit_tests/ tests/integration_tests/. Coverage reports can be accessed through the htmlcov/index.html file.

Good practice:

  • at least one test for every function in a module clearly testing the function’s behavior (including edge cases).

  • sort tests in the testing module in the same sequence as the functions in the module.

  • unit tests need to be fast.

Integration tests#

Integration tests should be written for every application and cover the most important use cases. Integration tests should follow the logic of the existing tests in simtools/tests/integration_tests. Any configuration file in the simtools/tests/integration_tests/config directory is used for testing.

For testing a single applications, use the -k option to select the test by name:

pytest -v -k "simtools-convert-all-model-parameters-from-simtel" tests/integration_tests/test_applications_from_config.py

To run a specific tests, use the -k option with the test name:

pytest -v -k "simtools-convert-all-model-parameters-from-simtel_num_gains" tests/integration_tests/test_applications_from_config.py

This runs to run the tool for the specific test called num_gains.

The integration test module allows for additional output tests (see the simtools/tests/integration_tests/config directory for examples).

Test that a given output file exists:

  INTEGRATION_TESTS:
    - OUTPUT_FILE: ray-tracing/results/ray-tracing-North-LSTN-01-d11.0km-za20.0deg_validate_optics.ecsv

Compare tool output with a given reference files (in the following example with a tolerance of 1.e-2 for floating point comparison):

REFERENCE_OUTPUT_FILES:
  - REFERENCE_FILE: ray-tracing/results/ray-tracing-North-LSTN-01-d11.0km-za20.0deg_validate_optics.ecsv
    TOLERANCE: 1.e-2

This is implemented for any astropy table-like file.

Test for a certain file type:

- FILE_TYPE: json

Model versions for integration tests#

The integration tests run for two different model versions, defined in the matrix in the CI-integrationtests.yml workflow.

As model versions and definitions change, not all integration tests will work with all model versions. Use the entry MODEL_VERSION_USE_CURRENT in the configuration file to fix the model version to the one defined in the configuration file.

Testing utilities#

The pytest-xdist plugin is part of the developer environment and can be used to run unit and integration tests in parallel (e.g., pytest -n 4 to run on four cores in parallel).

Tests might pass just because they run after an unrelated test. In order to test the independence of unit tests, use the pytest-random-order plugin with pytest --random-order.

Profiling tests#

Tests should be reasonably fast.

To identify slow tests, run the tests with the --durations option to list e.g. the 10 slowest tests:

pytest --durations=10

For profiling, use the pytest-profiling plugin. Example:

pytest --no-cov --profile tests/unit_tests/utils/test_general.py

To generate flame graphs for the profiling results:

pytest --no-cov --profile-svg tests/unit_tests/utils/test_general.py

(the installation of graphviz is required to generate the graphs)

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