EventedStreamReader not really emitting OnCompleteLine() per each line received

[dgaspar]

Describe the bug

EventedStreamReader's Run() method sometimes reads chunks containing multiple \n, but it only cares about the first \n it sees, and buffers the rest. The problem is when the chunk is the last output coming of npm during npm run serve, for a while. The remaining buffer is not notified (OnCompleteLine() is not called).

The risk is WaitFor(Regex regex) randomly missing the opportunity to finish, because it might miss some lines, as it listens to onReceivedLineHandler, and not to chunk events.

To Reproduce

Steps to reproduce the behavior:

1. ASP.Net Core 2.2 with Spa extensions;
2. tricky to reproduce: the app reads from npm's stdout a stream chunk that contains multiple \n characters in it;
3. notice how only the first chunk (until the first \n) gets notified to the event listeners, the rest doesn't.

Expected behavior

I would expect one call to OnCompleteLine() per actual line.

[mkArtakMSFT]

Thanks for contacting us, @dgaspar.
Would you be interested in sending us a PR for this? We'll happily consider it.

[mkArtakMSFT]

Thanks for your contribution, @dgaspar👍