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

[Vladimir Sementsov-Ogievskiy <vsementsov@virtuozzo.com>]

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


> +                run_command="$PYTHON $seq"
> +            else
> +                run_command="false"
> +                echo "Unsupported Python version" > $seq.notrun
> +            fi
>           else
>               run_command="./$seq"
>           fi
> 


-- 
Best regards,
Vladimir