[git-buildpackage] [PATCH 09/11] Command: pipe stdout to sys.stdout

[Guido Günther]

On Thu, Feb 05, 2015 at 05:31:32PM +0200, Markus Lehtonen wrote:
> Pipe stdout of the (child) command to sys.stdout of the caller. This
> makes Python nose to correctly capture the output of the child command,
> too, which in turn suppresses a lot of spurious output when running
> nosetests.

We can capture stdout/stderr using a context manager like in
testutils/capture.py. I'd rather not use a doctest if we need these kind
of things for that case only.
Cheers,
 -- Guido

> 
> Signed-off-by: Markus Lehtonen <markus.lehtonen at linux.intel.com>
> ---
>  gbp/command_wrappers.py | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/gbp/command_wrappers.py b/gbp/command_wrappers.py
> index f8c50f1..074d30a 100644
> --- a/gbp/command_wrappers.py
> +++ b/gbp/command_wrappers.py
> @@ -23,6 +23,9 @@ import subprocess
>  import os
>  import os.path
>  import signal
> +import sys
> +import tempfile
> +
>  import gbp.log as log
>  
>  class CommandExecFailed(Exception):
> @@ -67,7 +70,14 @@ class Command(object):
>  
>          log.debug("%s %s %s" % (self.cmd, self.args, args))
>          self._reset_state()
> -        stdout_arg = subprocess.PIPE if self.capture_stdout else None
> +        if self.capture_stdout:
> +            stdout_arg = subprocess.PIPE
> +        else:
> +            # Pipe stdout of the child command to sys.stdout so that std*
> +            # capture in nosetests catches the output of the command, too. We
> +            # need to use a temporary file if sys.stdout is not a real file.
> +            stdout_arg = sys.stdout if hasattr(sys.stdout, 'fileno') else \
> +                                       tempfile.TemporaryFile()
>          stderr_arg = subprocess.PIPE if self.capture_stderr else \
>                                          subprocess.STDOUT
>          cmd = [ self.cmd ] + self.args + args
> @@ -84,6 +94,10 @@ class Command(object):
>                                       stdout=stdout_arg,
>                                       stderr=stderr_arg)
>              (self.stdout, self.stderr) = popen.communicate()
> +            # Write stdout content back to sys.stdout if the tempfile hack was used
> +            if stdout_arg not in [sys.stdout, subprocess.PIPE]:
> +                stdout_arg.seek(0)
> +                sys.stdout.write(stdout_arg.read())
>          except OSError as err:
>              self.err_reason = "execution failed: %s" % str(err)
>              self.retcode = 1
> -- 
> 2.1.4