Mocks are the Little-Death: Escaping the Mirage of Green Tests

“Mocks are the mind-killer. They are the little-death that brings total production failure. I will face my mocks. I will permit them to pass over me and through me. And when they have gone past, I will turn the inner eye to see their path. Where the mocks have gone there will be nothing. Only pure data will remain.” We’ve all walked the burning sands of the ‘Green Test, Broken Production’ mirage. Watching a sea of green is comforting, but it is a hollow victory. The true test comes when the code meets the deep desert of production and withers, leaving us to find that a mock ceased to reflect reality months ago. I grew tired of mocks lying to me and the extra complexity they bring. This led me back to a classic design pattern: the Command. The idea is simple: separate an action from its execution. I wanted a functional take on this, though: no classes, no mutation, just pure functions returning plain data. Most importantly, I wanted it without the academic vocabulary of category…