[lkitching]

I disagree that delegates and higher-order function are 'crap' or in any way more complicated than introducing interfaces that are injected though a centralised container. You could just as easily turn that argument around and say mocking and an overuse of interfaces come from your resistance to using small static methods. In C# Linq is almost entirely based on static methods and delegates and that is not harder to test as a result.

Static methods usually don't rely on any hidden state at all. The example originally given was for a graph operation which could just take the input graph as an argument and return the result. When your code is composed of small independent functions you don't need mocking and substitution at all. In my experience most uses of mocks come from functions that do too much in the first place.