Ensure all stream buffers are drained before exiting process in single run mode.

[kdrvn]

After investigating a strange behavior on running karma with TeamCity on Windows, I noticed the following issue.

When running the following command in PowerShell:

karma start --single-run | Out-File C:\test.out

The writing function is non-blocking/asynchronous & the written/piped data can be buffered, which could lead to some test results being lost.

Karma needs to ensure that all buffers have been drained or that the writing functions have completed (if they are non-blocking) before exiting the process.

[vojtajina]

Yep, I think we should use https://npmjs.org/package/exit

[DanTup]

I had the same issue in my Jasmine VS extension, and I fixed it in a much simpler way than what that module seems to do:

process.stdout.once('drain', function() {
    process.exit();
});

Not sure whether I've missed something; but this seems much simpler?

[vojtajina]

@DanTup yep we could do this. Actually, I just realized we might use the "exit" event (

karma/lib/server.js

Line 215 in b2ebc95

globalEmitter.emitAsync('exit').then(function() {

) which is used by all the components in the system to delay exit (eg. reporters writing a file). In the same way, we should wait for process.stdout to drain.