Description: A Zombie test is a type of test in the realm of test-driven development (TDD) that, although no longer relevant to the current code, continues to run in the test suite. These tests may have been useful in the past, but over time, the code has evolved, and the conditions that justified their existence have changed. Often, Zombie tests result from code that has been refactored or modified in such a way that the test no longer reflects the actual functionality of the system. However, despite their lack of relevance, these tests can still consume resources during the test suite execution, leading to confusion and increased test execution time. Identifying and removing Zombie tests is crucial for maintaining efficiency and clarity in the development process, ensuring that only tests that truly add value to the software lifecycle are executed. In summary, Zombie tests serve as a reminder of the importance of keeping code and tests updated and aligned with the current functionality of the system.
History: The term ‘Zombie test’ has emerged in the software development community as test-driven development (TDD) practices gained popularity since the 1990s. As teams adopted TDD, it became evident that some tests, while initially useful, became obsolete due to changes in the code. The need to identify and eliminate these ineffective tests became a topic of discussion in conferences and publications on best practices in agile development.
Uses: Zombie tests are primarily used to illustrate the importance of maintaining a clean and relevant test suite. In agile development environments, it is recommended to periodically review tests to identify those that no longer add value. This helps optimize test execution time and reduce confusion among developers regarding the functionality of the code.
Examples: An example of a Zombie test could be a test that verifies the functionality of a method that has been removed or replaced in the code. Although the test continues to run, it makes no sense in the current context of the software, which can lead to misleading results during automated testing.
