test: support testing transpiled code

[cjihrig]

This commit makes it possible to execute the tests after transpilation. This should provide additional confidence that the code shipped to npm works as intended.

I think we'll also want to integrate this into the CI. Should it be for every PR, or the release job only?

[mstruebing]

I think we should do this for every PR instead of only the release job.
That way we know for sure that the current code works and don't find out when we want to release.

[cjihrig]

Added to the PR job. It seems to work.

[brendandburns]

/lgtm
/approve

Thanks for doing this! We should run it on all PRs, otherwise it will be really painful whenever we try to do a release and things have been broken for a while.

[k8s-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

This pull-request has been approved by: brendandburns, cjihrig

The full list of commands accepted by this bot can be found here.

The pull request process is described here

Details

Needs approval from an approver in each of these files:

• OWNERS [brendandburns]

Approvers can indicate their approval by writing /approve in a comment
Approvers can cancel approval by writing /approve cancel in a comment