tearDownClass

TearDownClass is a class-level hook in Python's unittest framework. It is defined as a class method, typically using the signature @classmethod def tearDownClass(cls):, and it runs after all test methods in a TestCase subclass have completed. Its purpose is to release or clean up resources that were allocated for the entire class, rather than for individual tests.

Definition and invocation: tearDownClass is invoked once after the whole set of tests in the class has finished. It is used to tear down class-wide fixtures, such as shared database connections, file handles, or network resources. Note that if setUpClass encounters an error, tearDownClass is not called; likewise, if tests fail or succeed, tearDownClass will still run if setUpClass completed successfully.

Usage considerations: Because it executes only once per class, tearDownClass is suitable for expensive resources that should not be recreated for each test method. It complements per-test cleanup methods like tearDown, which run after each individual test. Resources accessed in tearDownClass are typically stored on the class (e.g., cls.db) rather than on the test instance.

Relation to other lifecycle methods: setUpClass runs once before any tests in the class; tearDownClass runs once after all tests have finished. In contrast, setUp and tearDown run before and after each test method, respectively. Together, these hooks allow precise control over resource management at both the class and test levels.

Example use case: a test class that interacts with a shared in-memory database can establish the connection in setUpClass and close it in tearDownClass, ensuring the connection is available to all tests while avoiding repeated setup and teardown.