i actually writing a test case who check code style with flake8 i interested in retrieve only the name of the files with errors not the error itself, so after some research i trying to capture the stdout of flake8 and write the next code out, err = sys.stdout, sys.stderr dummy = StringIO() sys.stdout, sys.stderr = dummy, dummy pep8 = engine.get_style_guide() pep8.paths = [....] report = pep8.check_files() sys.stdout, sys.stderr = out, err Always dummy.getvalue() comes empty. Its another way to retrieve the list of files who fail the check? also i try to write my own report class who inherit from BaseQReport and add redefining a error method with a multiprocessing.Queue for communication but don't work Sorry for my poor english grammar regards.