Testing applications utilizing databases poses a challenge for backend developers, especially when aiming for unit tests rather than integration tests. While traditional methods like using real databases or Docker can be cumbersome, mocking offers an efficient alternative, particularly for isolating API behavior. The Elasticsearch Node.js client, designed for flexibility, can be mocked effectively by replacing its Connection component. The @elastic/elasticsearch-mock library facilitates this process by allowing developers to create custom mocks for requests, enhancing test speed and parallelization without altering other client components. This library supports both strict and loose mocks, dynamic paths, wildcards, and even simulates random failures, enabling robust testing scenarios. The approach ensures that only the HTTP layer is mocked, maintaining the integrity of other client functionalities, thus providing an efficient and error-free testing environment.