Earlier quoted context omitted.
> you can't generally mock a function With `dynamic` and `DynamicObject`/`ExpandoObject` proxies (or even lower level System.Dynamic/System.Linq.Expression fun) you can mock anything you want to in C#. Those tools go all the way back to the early days of Linq (and useful but somewhat broken DLR visions like IronPython). If you need to time travel even further back in the .NET stack, or if you are just allergic to/dea…
I'm on of those people that had no idea about all this extra functionality- thanks for opening that door. Do you have any resources on the hand writting "Fakes" patterns?
There are obviously good reasons auto-mocking frameworks became popular as it can be too easy to fall into performance traps or to try to maintain two separate dependency stacks (and get dangerously close to all of your units tests as just baroquely complex integration tests), one of which may easily get out of date/diverge and is extremely fragile, especially if you don't have good abstractions up front. It's too easy for how easy you can build your "fake" data sources to accidentally create a lower common denominator of what you can safely test, either limiting the types of queries that you feel like you can add to production code (forcing you to avoid things that your production DB supports, but an SQLite or In Memory storage can't easily fake) or create growing missing coverage boundaries between "testable" and "production" code.
On the flip side though, the benefits of hand-written fakes should be that you better prove out your abstractions and how they are factored (if it is too hard to manually fake a dependency, then maybe that becomes a sign that the dependency needs to be refactored and/or a better abstraction found for it), and the tests overall more resemble your production code and how it operates in the wild. (Versus how I feel excessively mocked code starts to resemble "stage plays" that don't necessarily approach or model real world usage and behavior and it often remains too easy to "stage play" even when your abstractions are wrong/not helping you enough.)