Chunky integration testing is supported. Fine-grained unit testing is ... so-so. If you have units that don't interact with the standard library you can pin dow

Chunky integration testing is supported. Fine-grained unit testing is ... so-so. If you have units that don't interact with the standard library you can pin down a lot of behaviour. But if you touch the standard library, which in a systems language is going to happen a bit, then isolating your own code is basically impossible. You are stuck with integration testing only. Mocking, faking, stubbing and whatnot frequently blow your feet off if you use them indiscriminately. But sometimes they are the best way to test code because you can perform controlled experiments with variables that you control. Go's standard library is riddled with physical structs that cannot be substituted for any kind of double. Basically, they don't follow their own advice to interface all the things.