Advanced unit testing patterns in Go

The article explores advanced testing techniques in Go, focusing on enhancing the effectiveness of testing code beyond basic methods. It delves into patterns such as mocking, test fixtures, test helpers, and golden files, demonstrating their application in real-world scenarios. The text highlights testing HTTP handlers by decoupling dependencies, allowing easier isolation for testing, and emphasizes the use of table-driven tests for handling various inputs. Mocking external dependencies is discussed, particularly through creating custom interfaces to simulate HTTP client interactions without real network calls. The article also covers leveraging external data stored in testdata directories for testing purposes, using base64 encoding as an example, and introduces golden files to manage expected outputs in tests, with goldie as a tool to facilitate this process. Throughout, the emphasis is on maintaining test efficiency and accuracy while avoiding direct dependencies on external systems.