posts/async-tests-in-elixir/

[giscus[bot]]

posts/async-tests-in-elixir/

It can be hard to keep tests asynchronous as Elixir applications grow in size and complexity. Let's see why, and explore fixes.

https://andrealeopardi.com/posts/async-tests-in-elixir/

[miros]

But you might not be testing the public API for MetricsBuffer directly—maybe your code-under-test is calling out to that. How do you pass stuff around?

By injecting dependencies instead of hardcoding them.
I find it ironic that so many people think, that explicitly passing things as parameters to functions (in functional language!) is too complex.

[whatyouhide]

Often, this quickly becomes a tangled mess of passing parameters around many layers. I don't think it's a complex approach, I do think it's quite un-ergonomic in many real-world cases, especially in large applications.

[venkatd]

One of my favorite books on software development, A Philosophy of Software Design, has a passage that articulates the problem with always passing dependencies around everywhere:

Pass-through variables add complexity because they force all of the
intermediate methods to be aware of their existence, even though the methods
have no use for the variables. Furthermore, if a new variable comes into
existence (for example, a system is initially built without support for certificates,
but you later decide to add that support), you may have to modify a large number
of interfaces and methods to pass the variable through all of the relevant paths.

So in fact, it can get complex to "explicitly" pass around parameters all the time, especially if it's something that only the lowest layers care about!

[krasenyp]

My suspicion is that Elixir folks are really OOP aficionados in disguise. I see singletons, globally named processes, everywhere and using global switches to change implementations. We need an ergonomic way to use something like the Reader monad. It'd allow us to thread dependencies without hassle.