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Comment by SR2Z | Hacker News Reader

It's bizarre to me that we live in a world where whole machines and their networking stack can be spun up and virtualized and yet integration testing STILL actually has to go out and touch a real resource running on a different machine.

Yeah, obviously this isn't gonna work for embedded development, but not that many people have that specific problem. Is it really so hard to spin up ephemeral testing clusters on a single machine? Everywhere that I've seen it done, it's a horrible kludge of scripts and hacks that's almost as difficult to understand as the code under test.

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When you are integrating to other people's stacks, then you need a test facility where people can bring systems together, sometimes there are also physical elements that are required.

I work in Automatic Fare Collection (think railway passenger gates, ticket vending, contactless readers, bus driver consoles and readers etc as well as the backends that deal with the fare calculation and payments).

There are usually multiple vendors involved, and even with the best API and interface documentation and individual system testing against the specifications, you still need to bring the entire environment, including the hardware, together.

These ITFs (Integration Test Facilities) tend to be in existence for the life of the systems, including after hardware refreshes etc.

Yes you can test performance with jmeter etc, but sometimes you need 20 people walking in a circle between an entrance gate and an exit gate.

Fair enough, but IMO even a system like this one should have good mock implementations of the system hardware, down to and including a simple simulator for the physical layout of people near the machine.

In past years I wouldn't say that, but these days it's so easy to get an LLM to write something like this plus a quick and dirty visualization.

I'm not saying this can be a replacement for a physical test setup, but it's so much easier to make changes when the tests can just give a clear cut "yes, this acts like you expect" or "no, this is broken."

At some point, it becomes hard to assert “we are NOT going to test the product the way a customer would actually use it”

Docker has made this much much easier than it used to be, and the ease of publishing images has led to many SaaS companies providing "dockerized" versions of their services.

I write a lot of Terraform to manage internal infrastructure with dependencies on other internal and external infrastructure that's outside of my control. I define a module parameter for each dependency (usually with a default value that points to the real service URL) and then create a second module that uses Docker to spin up and configure local instances of each dependency and overrides the corresponding parameter.

This makes local testing very straightforward: `terraform -chdir=tests apply`

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