http2: improve code coverage

[mcollina]

This is a meta-issue to improve the code coverage of http2.
As you can see in https://coverage.nodejs.org/coverage-342c5f9d4c2eb868/root/internal/http2/index.html, we have 79% code coverage, and we should definitely do better before it leaves experimental status.

Feel free to reach out to @nodejs/http2 if you have any questions on how to test this part of Node.js.

[TimothyGu]

There's https://github.com/http2/http2-test, which happens to be written to run on Node.js. We should look into integratingporting that.

[mcollina]

@TimothyGu thats fairly old and for the http2 module published on npm. I think we need something specific for core in test/parallel.

[benhalverson]

@mcollina I'd like to help improve the test coverage. Where should I look to get started on http2?

[jasnell]

@benhalverson ... reach out any time with any questions you may have.

[ssbrewster]

@jasnell should it be one PR per test file added or multiple test files in one PR (if it matters)?

[mcollina]

@ssbrewster it's ok if it's a PR with 2-3 files if they are connected to the same area that you are testing. If you are adding some tests for sendFile, then it's ok if they all live in the same commit/PR. If they are related to different areas of the API, then fire multiple PRs.

[ssbrewster]

Great, thanks for the clarification @mcollina