Re: [PATCH v2 4/5] check-ignore: allow incremental streaming of queries via --stdin

[Adam Spiers <git@adamspiers.org>]

On Thu, Apr 11, 2013 at 03:11:32PM -0400, Jeff King wrote:
> I always get a little nervous with sleeps in the test suite, as they are
> indicative that we are trying to avoid some race condition, which means
> that the test can fail when the system is under load, or when a tool
> like valgrind is used which drastically alters the timing (e.g., if
> check-ignore takes longer than 1 second to produce its answer, we may
> fail here).

Agreed, especially here where my btrfs filesystems see fit to kindly
freeze my system for a few seconds many times each day :-/

> Is there a simpler way to test this?
> 
> Like:
> 
>   # Set up a long-running "check-ignore" connected by pipes.
>   mkfifo in out &&
>   (git check-ignore ... <in >out &) &&
> 
>   # We cannot just "echo >in" because check-ignore
>   # would get EOF after echo exited; instead we open
>   # the descriptor in our shell, and then echo to the
>   # fd. We make sure to close it at the end, so that
>   # the subprocess does get EOF and dies properly.
>   exec 9>in &&
>   test_when_finished "exec 9>&-" &&
> 
>   # Now we can do interactive tests
>   echo >&9 one &&
>   read response <out &&
>   test "$response" = ... &&
>   echo >&9 two &&
>   read response <out &&
>   test "$response" = ...
> 
> Hmm. Maybe simpler wasn't the right word. :) But it avoids any sleeps or
> race conditions.

The shell source is strong with this one ;-)

Congrats - I first tried with FIFOs (hence my other patch which moves
the PIPE test prerequisite definition into the core framework - the
original intention was to reuse it here) but failed to get it working.
I'll re-roll using your approach.