Prevent first Python command being lost

[anthonykim1]

Fixes: #22673
Fixes: #22545
Fixes: #22691

Making best effort to address issue where very first command sent to REPL via Terminal gets ignored, or gets pasted both in Terminal and in REPL.

With the fix, we observe whether Python REPL is launched in Terminal via VS Code's onDidWriteTerminalData and send the command, or wait three seconds as a fallback mechanism.

These two combined together will significantly reduce or resolve all-together the chance of very first command being swollen up or gets pasted twice in Terminal and REPL previously where it did not have context of whether Python REPL instance have started inside the Terminal or not.

[hediet]

Line 71 seems to do this already.
Generally, this code seems to be quite difficult to read (a for loop in an event listener in a promise that is returned by a promise), I suggest to reduce nesting a bit.

[anthonykim1]

Thank you for the feedback!! @hediet.
It's little tricky right now, since I wanted a promise that always returned true, maximum three second or faster if we see that Python REPL has launched before.
I definitely thought about removing the second timeout, but in testing scenario, I would get promise rejection since it could not read the ">>>" from TerminalData like how it would normally read from user's terminal when we launch Python REPL from shell of their choice.

[hediet]

but in testing scenario, I would get promise rejection

I don't understand why this would happen. Are you sure? race ignores future rejections.

[anthonykim1]

Yeah, I found it pretty odd too.. Perhaps its because during testing, we don't have "mocking" of Terminal write data containing the ">>>" that I check for to see if Python REPL has launched?? hence maybe thats why it may be giving rejection before we pass with the 3 second condition.