Re: verbose testsuite output contains 1M newlines

[Ralf Wildenhues]

* Eric Blake wrote on Sun, Nov 23, 2008 at 03:56:49PM CET:
> According to Ralf Wildenhues on 11/23/2008 6:23 AM:
> > running
> >   make check-local TESTSUITEFLAGS=-v
> > 
> > on M4 (git master) produces lots of output on GNU/Linux/bash.

> Hmm, this particular test _has_ to generate more than a megabyte of output
> in order to trigger the code path in m4 being tested (namely, that m4
> starts using temporary files after it collects enough in-memory diversion
> output).  The problem stems from the fact that by default, when you
> specify [stdout] as the third argument to AT_CHECK, autotest emits code
> that both collects the file stdout (good) and copies the resulting file
> into the log (annoying), and when -v is in effect, tees that copy to the
> terminal (bad).  I think the idea behind this decision was that
> testsuite.log should be self-contained, with everything needed to
> reproduce why a test failed.

Yes.  I think the Autotest behavior is more or less ok for most tests.
Maybe we can have AT_CHECK modifiers or sister macros that allow to
specify that some output may not be suitable for the screen or the log
file, due to size or content such as control characters.

> The point of specifying [stdout] is that we plan on processing the
> resulting output file later on, so maybe we should quit trying to copy the
> captured file into the logs.

Naah, I like the default.

> Maybe we should revisit this, and change it
> so that the file is just collected, with nothing output into the log.  Or
> even add a heuristic, where only the first and last 10 lines of the
> resulting file are output into the log.  If the test passed, then the log
> doesn't need megabytes of information; and if the test fails, hopefully
> trimming out the middle of the file from the log still leaves enough
> information in the log to help diagnose what went wrong; the full file
> will still be available in testsuite.dir/nnn/stdout if the log was
> insufficient by itself.

But only if a later test in the same group did not overwrite it.

> > Hmm, maybe this is introduced by some Autotest changes in Autoconf even.
> 
> No, I think this behavior is present even with 2.62, before we started
> using functions in autotest (although I haven't tested yet).

Thanks for checking.

Cheers,
Ralf