Left fold

Following the introduction on this series on a previous post, we will now talk about dependency injection and how it has the effect of allowing for more testable code. Sometimes when I talk about this concept it is difficult to explain the effect that applying it might have on the tests. For that reason I think it is better to demonstrate with a near-real-world situation. Obviously, keep in mind this is not real code, so don't worry about the design or implementation details that don't contribute to the point being discussed. The code As you can see, it is simple. There's a class called ShipManager (what else?) that receives position updates for the ships. It keeps the last position reported from each ship and does some calculation to see how much the ship moved. It assigns some values to the update and finally it persists the final version of the update. How do we start testing? When you think about it, tests are dead simple. A test either passes or it doesn

I started testing my code automatically a couple of years in after starting my career. Working in a small company, there weren't really incentives for us to automate testing and we were not following any kind of best practices. Our way of working was to write the code, test it manually and then just Release It ™ , preferably on a Friday of course. I'm sure everyone can relate to this at some point in their career, because this is a lot more common than the Almighty Programming Gods of the Internet make us believe. I find that the amount of companies that actually bother writing tests for their production code is a fraction of the whole universe. I know some friends who work in pretty big companies with big names in the industry and even there the same mindset exists. Of course, at some point in time our code turned into a big pile of shit . Nobody really knew what was going on and where. We had quantum-level switcheroo that nobody really wanted to touch, and I suspect it i

This post is a follow up on the previous post. It presents an approach on how to return values from a method. I got some great feedback both good and bad from other people, and with that I will present now the updated code taking that feedback into account. Here is the original: And the modified version: Following is some of the most important feedback which led to this. Make it an immutable struct This was a useful one. I can't say that I have ever found a problem with having the Result type as a class, but that is just a matter of scale. The point of this is that now we avoid allocating memory in high usage scenarios. This was a problem of scale, easily solvable. Return a tuple instead of using a dedicated Result type The initial implementation comes from a long time ago, when C# did not have (good) support for tuples and deconstruction wasn't heard of. You would have to deal with the Tuple type, which was a bit of a hassle. I feel it would complicate the