Create exercise versioning policy based on Haskell track

[sshine]

The Haskell track uses the version property in stack's package.yaml to contain the version of problem-specifications for the given exercise. See for example exercism/haskell@003f9d9 's 1.3.0.6: 1.3.0 is the version in problem-specifications bumped in exercism/problem-specifications#1293 and 6 is a serially incremented value across any local change to the exercise.

We could go with the same versioning policy as the Haskell track, but since there's less traffic on the Ocaml track's GitHub, we could do with just the problem-specifications version number for each exercise.

Here are three suggestions as to where we can place the version number:

1. We could place it in a comment at the top of test.ml:

   (* Test version: 1.3.0 *)
   

   Embedding information in comments is less ideal.

2. We could place it as a top-level definition in test.ml:

   let test_version = "1.3.0"
   

   Since test.ml auto-executes unconditionally, we could change all test.ml files to inspect Sys.interactive (equivalent to Python's if __name__ == "__main__").

3. We could embed a version number in dune-project:

   (version 1.3.0)
   

   This most closely resembles how the Haskell track does it.

[sshine]

I'm voting for

• just the problem-specifications version, and
• embed a version number in dune-project.

[stevejb71]

See exercism/exercism#4266

I'm not sure this change would be so useful (though I'm willing to listen to justifications for it).

[sshine]

I've read that issue, and the obsolete version tracking is not the same as what I'm suggesting that we adopt from the Haskell track.

A hacky workaround that we used in many tracks was to add a version to the exercise tests, and the test suite would include a failing assertion that included that version number.

So some test suites tried to have test versioning as a dynamic part of the tests so when you test their version with a test suite that is ahead, it detects which tests to apply. This is a non-issue now as exercism download uses the test suite that corresponds in time to when they downloaded the exercise.

What I'm proposing is that we keep track of how up to date we are with problem-specifications so new test cases can propagate to the Ocaml track.

[stevejb71]

That may be worth a go... should probably be in the tools folder.

[sshine]

By closing this, I've marked the policy as chosen.

I'll create another issue in which we can track progress.