(CI) Have a way to generate and verify exitence of golden tests

[KtorZ]

Context

API breaking changes are bad and also tricky to identify somehow. Right now, there's nothing really helping us not breaking the API apart from our own discipline. Despite being disciplined, something can also slip through our attention and get merged, unnoticed. A simple step towards this would be to add a few golden tests to make sure that API types aren't actually changing in a non backward-compatible ways.

If a given API type has one or a few associated golden test, hopefully, upon making a change, the underlying change would fail. Then, we can assess whether this change is a breaking change or just a soft extension.

Decision

We want to write such golden tests for existing API types. But because tracking the existence of those tests can be tedious, we'd also like ideally, to have a way to enforce the existence of such tests in such way that the code wouldn't even compile without us specifying them.
Since the API is completely defined in terms of a single type by the mean of Servant combinators, we can work out some checks using a generic approach.

Acceptance Criteria

1. • Each API types that is exposed must have one or more golden tests for its corresponding JSON or HttpApiData instances.
2. • The existence of such tests should be enforced for existing and future types automatically.

---

PR

Number	Base
#?	develop

QA

Criteria	Coverage
?	-

---

Retrospective

[Anviking]

We could also consider generating golden tests and writing them to disk automatically so that API changes are tracked in git. (This would likely require the modifications to the API being translated very well, and deterministically into changes to the golden tests though.)