discussion starter: specify ts version

[phryneas]

This is more a discussion starter than an actual PR right now - but it works.

I've been able to run the tests for all versions from 3.0 to 3.7 with this approach by installing the respective @testable-ts version and executing them like

TYPESCRIPT_PATH=@testable-ts/v3.7 yarn test

Do you think this approach has any merit?

[phryneas]

This has to be a 3.0 version of typescript because newer typescript versions make use of non-downward-compatible typescript features in their types.

So testing 3.0 with types of 3.7 does not work, while testing 3.7 with types from 3.0 works just fine - especially as these types are just being used to interpret the code of tsd itself (I am not sure but I believe outside of the test suite this would not play any role at all).

[phryneas]

This is where the magic happens: use the environment variable or fall back the shipped typescript version (current behaviour)

[phryneas]

@SamVerschueren it's been a while, do you have any feedback on this?

[SamVerschueren]

Hi @phryneas! Sorry for my late replies but started to allocate more time for tsd.

I believe this is somewhat where I want to go to yes. I believe it would be nice if you could specify the TS versions you want to test in the tsd config.

{
    "tsd": {
        "typescript": ">=3.2"
    }
}

Not sure yet about the syntax. But running tsd on this project would spawn multiple processes, for each version one, with the environment variable set like you did here manually.

That would be super cool!

What do you think?

[phryneas]

That would be pretty incredible although it might probably be necessary to skip some tests depending on TS version (no use running tests with as const in TS 3.1), so some way of specifying which files to run would be great.

[SamVerschueren]

Closing this as it's WIP currently. Feel free to discuss in the issue #47.