This adds an Exception that extends the Python stdlib subprocess.CalledProcessError.
The difference is that the str() method of this exception also adds the stdout/stderr logs. In effect, if this exception goes unhandled, Python will print the output in a visually distinct wrapper to the terminal so that it's easy to spot in a sea of traceback information. Signed-off-by: John Snow <js...@redhat.com> Reviewed-by: Eric Blake <ebl...@redhat.com> Reviewed-by: Hanna Reitz <hre...@redhat.com> --- python/qemu/utils/__init__.py | 39 +++++++++++++++++++++++++++++++++++ 1 file changed, 39 insertions(+) diff --git a/python/qemu/utils/__init__.py b/python/qemu/utils/__init__.py index 5babf40df2..904eb0de33 100644 --- a/python/qemu/utils/__init__.py +++ b/python/qemu/utils/__init__.py @@ -18,6 +18,7 @@ import os import re import shutil +from subprocess import CalledProcessError import textwrap from typing import Optional @@ -26,6 +27,7 @@ __all__ = ( + 'VerboseProcessError', 'add_visual_margin', 'get_info_usernet_hostfwd_port', 'kvm_available', @@ -121,3 +123,40 @@ def _wrap(line: str) -> str: os.linesep.join(_wrap(line) for line in content.splitlines()), _bar(None, top=False), )) + + +class VerboseProcessError(CalledProcessError): + """ + The same as CalledProcessError, but more verbose. + + This is useful for debugging failed calls during test executions. + The return code, signal (if any), and terminal output will be displayed + on unhandled exceptions. + """ + def summary(self) -> str: + """Return the normal CalledProcessError str() output.""" + return super().__str__() + + def __str__(self) -> str: + lmargin = ' ' + width = -len(lmargin) + sections = [] + + # Does self.stdout contain both stdout and stderr? + has_combined_output = self.stderr is None + + name = 'output' if has_combined_output else 'stdout' + if self.stdout: + sections.append(add_visual_margin(self.stdout, width, name)) + else: + sections.append(f"{name}: N/A") + + if self.stderr: + sections.append(add_visual_margin(self.stderr, width, 'stderr')) + elif not has_combined_output: + sections.append("stderr: N/A") + + return os.linesep.join(( + self.summary(), + textwrap.indent(os.linesep.join(sections), prefix=lmargin), + )) -- 2.34.1