added spec to test all DefinitelyTyped packages

[SrTobi]

I think it's a good idea to test against the DefinitelyTyped code base.
This pr adds a spec that tries to import every project on DefinitelyTyped (output goes into a temporary file).

It yields (at the moment) 5935 test cases.

(this incorporates some of the currently open prs)

I'm not really happy with how DefinitelyTyped has to be cloned manually into the root directory at the moment. I tried to do it with sbt, but in the end the manual way was easier and works just as good 😄. I made a small script that makes it even easier

[sjrd]

Thank you for your interest.

I'm afraid there are several issues with trying to do this:

• Currently the test suite doesn't pass, and the CI even less so. We can't consider this PR until the CI passes, one way or another, as otherwise new failures will be hidden by those.
• Even if the CI passes now, depending on the master of DefinitelyTyped is a volatile dependency, which means that upstream changes can break our build at any time.

[SrTobi]

yeah, I see what you mean. I still think this is a good idea to have this, in order to find bugs.

Not sure how to proceed though... there are clearly more things that have to be fixed until this will be a passing test... I would suggest to set it to ignore but then it will stiff fail for people running all tests locally.

But I am right in assuming that all valid typedefinitions should be importable by this tool, right?

For the issue regarding master dependencies, we could use the current hash of master.

[sjrd]

Maybe you could use a blacklist of tests that are known not to pass?

I'm not really happy with how DefinitelyTyped has to be cloned manually into the root directory at the moment. I tried to do it with sbt, [...]

You can do it like at
https://github.com/scala-js/scala-js/blob/7a794db9d91b68c6f4ba7d28e52eb09d5c9c6127/project/Build.scala#L1693-L1720