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| -rw-r--r-- | HACKING.rst | 34 |
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diff --git a/HACKING.rst b/HACKING.rst index 0dec469c..763f83aa 100644 --- a/HACKING.rst +++ b/HACKING.rst @@ -143,3 +143,37 @@ Cloud Config Modules * Any new modules should use underscores in any new config options and not hyphens (e.g. `new_option` and *not* `new-option`). + +Unit Testing +------------ + +cloud-init uses `pytest`_ to run its tests, and has tests written both +as ``unittest.TestCase`` sub-classes and as un-subclassed pytest tests. +The following guidelines should be following: + +* For ease of organisation and greater accessibility for developers not + familiar with pytest, all cloud-init unit tests must be contained + within test classes + + * Put another way, module-level test functions should not be used + +* pytest test classes should use `pytest fixtures`_ to share + functionality instead of inheritance +* As all tests are contained within classes, it is acceptable to mix + ``TestCase`` test classes and pytest test classes within the same + test file + + * These can be easily distinguished by their definition: pytest + classes will not use inheritance at all, whereas ``TestCase`` + classes will subclass (indirectly) from ``TestCase`` + +* pytest tests should use bare ``assert`` statements, to take advantage + of pytest's `assertion introspection`_ + + * For ``==`` and other commutative assertions, the expected value + should be placed before the value under test: + ``assert expected_value == function_under_test()`` + +.. _pytest: https://docs.pytest.org/ +.. _pytest fixtures: https://docs.pytest.org/en/latest/fixture.html +.. _assertion introspection: https://docs.pytest.org/en/latest/assert.html |