Sadly, the vast majority of developers don’t know or care to learn the nuanced differences between spies, stubs, fakes, mocks; or what a “partial” test double is and why they’re usually a bad idea. As a result, it’s not helpful when this jargon leaks into the API of test double libraries. In testdouble.js, there is a single type of test double function, designed to stand-in for any real function y