Re: [PATCH 4/4] iotests: make qemu_img raise on non-zero rc by default

[Eric Blake]

On Tue, Feb 15, 2022 at 05:08:53PM -0500, John Snow wrote:
> re-configure qemu_img() into a function that will by default raise a
> VerboseProcessException (extended from CalledProcessException) on
> non-zero return codes. This will produce a stack trace that will show
> the command line arguments and return code from the failed process run.
> 
> Users that want something more flexible (There appears to be only one)

s/There/there/

> can use check=False and manage the return themselves.
> 
> Signed-off-by: John Snow <jsnow@redhat.com>
> ---
>  tests/qemu-iotests/257        |  8 ++++--
>  tests/qemu-iotests/iotests.py | 53 +++++++++++++++++++++++++++++++----
>  2 files changed, 53 insertions(+), 8 deletions(-)
> 

> +def qemu_img(*args: str, check: bool = True, combine_stdio: bool = True
> +             ) -> subprocess.CompletedProcess[str]:
> +    """
> +    Run qemu_img, returning a CompletedProcess instance.
> +
> +    The CompletedProcess object has args, returncode, and output properties.
> +    If streams are not combined, It will also have stdout/stderr properties.

s/It/it/

> +
> +    :param args: command-line arguments to qemu_img.
> +    :param check: set to False to suppress VerboseProcessError.
> +    :param combine_stdio: set to False to keep stdout/stderr separated.
> +
> +    :raise VerboseProcessError:
> +        On non-zero exit code, when 'check=True' was provided. This
> +        exception has 'stderr', 'stdout' and 'returncode' properties
> +        that may be inspected to show greater detail. If this exception
> +        is not handled, The command-line, return code, and all console

s/The/the/

> +        output will be included at the bottom of the stack trace.
> +    """

> @@ -469,8 +511,9 @@ def qemu_nbd_popen(*args):
>  
>  def compare_images(img1, img2, fmt1=imgfmt, fmt2=imgfmt):
>      '''Return True if two image files are identical'''
> -    return qemu_img('compare', '-f', fmt1,
> -                    '-F', fmt2, img1, img2) == 0
> +    res = qemu_img('compare', '-f', fmt1,
> +                   '-F', fmt2, img1, img2, check=False)
> +    return res.returncode == 0

Not sure why there was so much Mid-sentence capitalization ;)

Seems useful, although it is at the limits of my python review skills,
so this is a weak:

Reviewed-by: Eric Blake <eblake@redhat.com>

-- 
Eric Blake, Principal Software Engineer
Red Hat, Inc.           +1-919-301-3266
Virtualization:  qemu.org | libvirt.org