computer-playbook/docs/contributing/code/tests/unit.md

Unit Tests

This page is the SPOT for unit testing requirements, framework, and structure. Run unit tests with make test-unit.

Framework

• You MUST use Python unittest as the test framework.
• Tests MUST live under tests/unit/.
• Mirror the source tree: a file at plugins/lookup/service.py gets its tests at tests/unit/plugins/lookup/test_service.py.

Requirements

• You MUST add or update unit tests for every *.py file you touch.
• Each test MUST cover one isolated behavior. Do not test multiple concerns in a single test method.
• You MUST NOT write tests that only assert a file contains a string.
• You MUST NOT write tests for non-executable files such as .yml or .j2. Test the code that consumes them instead.
• You SHOULD name test methods after the behavior they verify, not the function name alone (e.g. test_needed_false_when_disabled).
• You SHOULD cover edge cases — empty inputs, missing keys, boundary values — not only the happy path.
• You MAY use unittest.mock to isolate the unit under test from Ansible internals or external state.

How to Create

1. Identify the module under test (e.g. plugins/lookup/service.py).
2. Create the matching test file under tests/unit/ if it does not exist.
3. Subclass unittest.TestCase.
4. Write one method per behavior. Build hypotheses before writing assertions.
5. Run make test-unit and verify all tests pass.

Running Specific Tests

Use TEST_PATTERN to scope the test run to a single file or a glob:

# Run a single test file
TEST_PATTERN=test_my_module.py make test-unit

# Run all files matching a prefix
TEST_PATTERN=test_applications*.py make test-unit