testfüggség

Testfüggőség, commonly translated as "test dependency" or "test coupling," refers to a situation in software development where the outcome of one test relies on the successful execution or state left behind by another test. This can manifest in several ways, such as tests that must be run in a specific order, tests that modify shared data that subsequent tests depend on, or tests that assume a certain environment setup performed by a previous test.

The primary issue with testfüggőség is that it makes tests unreliable and difficult to maintain. If a test fails due to a dependency on a previous test that also failed, it can create a cascade of errors that obscure the root cause of the problem. This also makes it challenging to run tests in isolation, which is a fundamental principle of good unit testing. Isolated tests are easier to debug, understand, and refactor.

To mitigate testfüggőség, developers strive to create independent tests. This is often achieved through techniques like setting up a clean state before each test (e.g., using test fixtures or mocking), ensuring that each test verifies a specific, isolated piece of functionality, and avoiding shared mutable state between tests. While some level of integration testing inherently involves dependencies between components, unit tests should ideally be designed to be as independent as possible to provide the clearest and most actionable feedback.