Re: [RFC PATCH 0/2] qtest: Log verbosity changes

[Markus Armbruster <armbru@redhat.com>]

Daniel P. Berrangé <berrange@redhat.com> writes:

> On Fri, Sep 06, 2024 at 10:52:53AM +0100, Peter Maydell wrote:
>> On Fri, 6 Sept 2024 at 09:14, Daniel P. Berrangé <berrange@redhat.com> wrote:
>> >
>> > On Fri, Sep 06, 2024 at 08:16:31AM +0200, Thomas Huth wrote:
>> > > On 05/09/2024 23.03, Fabiano Rosas wrote:
>> > > > Hi,
>> > > >
>> > > > This series silences QEMU stderr unless the QTEST_LOG variable is set
>> > > > and silences -qtest-log unless both QTEST_LOG and gtest's --verbose
>> > > > flag is passed.
>> > > >
>> > > > This was motivated by Peter Maydell's ask to suppress deprecation
>> > > > warn_report messages from the migration-tests and by my own
>> > > > frustration over noisy output from qtest.
>> 
>> This isn't what I want, though -- what I want is that a
>> qtest run should not print "warning:" messages for things
>> that we expect to happen when we run that test. I *do* want
>> warnings for things that we do not expect to happen when
>> we run the test.
>
> Currently we just allow the child QEMU process stdout/err
> to inherit to the qtest program's stdout/err. With that
> approach we have to do filtering at soruce (ie in QEMU
> itself). I feel that in general it is a bad idea for the
> program being tested to alter itself to suit the test
> suite, not least because two different parts of the test
> suite may have differing views about what messages they
> want to ignore vs display.
>
> We could address this be switching to the model used
> with IO tests.  Always capture the child QEMU process
> stdout/err to a pipe. The test program can apply regex
> filters to cull output that is expected & irrelevant,
> and then print out whatever is left over on its own
> stderr.
>
> That way all the filtering of undesirable messages would
> be exclusively in the test suite, not QEMU itself.

Point.