Re: [PATCH v2 1/2] iotests: Require Python 3.6 or later

[Kevin Wolf <kwolf@redhat.com>]

Am 20.09.2019 um 10:40 hat Vladimir Sementsov-Ogievskiy geschrieben:
> 19.09.2019 19:29, Kevin Wolf wrote:
> > Running iotests is not required to build QEMU, so we can have stricter
> > version requirements for Python here and can make use of new features
> > and drop compatibility code earlier.
> > 
> > This makes qemu-iotests skip all Python tests if a Python version before
> > 3.6 is used for the build.
> > 
> > Suggested-by: Eduardo Habkost <ehabkost@redhat.com>
> > Signed-off-by: Kevin Wolf <kwolf@redhat.com>
> > ---
> >   tests/qemu-iotests/check | 13 ++++++++++++-
> >   1 file changed, 12 insertions(+), 1 deletion(-)
> > 
> > diff --git a/tests/qemu-iotests/check b/tests/qemu-iotests/check
> > index 875399d79f..588c453a94 100755
> > --- a/tests/qemu-iotests/check
> > +++ b/tests/qemu-iotests/check
> > @@ -633,6 +633,12 @@ then
> >       export SOCKET_SCM_HELPER="$build_iotests/socket_scm_helper"
> >   fi
> >   
> > +python_usable=false
> > +if $PYTHON -c 'import sys; sys.exit(0 if sys.version_info >= (3,6) else 1)'
> > +then
> > +    python_usable=true
> > +fi
> > +
> >   default_machine=$($QEMU_PROG -machine help | sed -n '/(default)/ s/ .*//p')
> >   default_alias_machine=$($QEMU_PROG -machine help | \
> >      sed -n "/(alias of $default_machine)/ { s/ .*//p; q; }")
> > @@ -809,7 +815,12 @@ do
> >           start=$(_wallclock)
> >   
> >           if [ "$(head -n 1 "$source_iotests/$seq")" == "#!/usr/bin/env python" ]; then
> > -            run_command="$PYTHON $seq"
> > +            if $python_usable; then
> 
> hmm I wanted to say that this should not work, as python_usable is a
> string. But I checked and see - it's work. Wow. Googled. And now I
> understand that here "false" or "true" command is called, to obtain
> it's return value.. I don't like bash and don't know its best
> practice, but I'd prefer python_usable to be just return value of your
> python command, like
> 
> above:
> 
>    $PYTHON -c 'import sys; sys.exit(0 if sys.version_info >= (3,6) else 1)'
>    python_usable=$?
> 
> and here:
> 
>    if [ $python_usable -eq 0 ]; then

I'm just trying to be consistent with other variables used in the
'check' script. It has many boolean variables and they all end up
calling the true/false commands.

And actually I think the version used is easier to read, even if maybe
not as easy to understand why exactly it works.

Kevin