def assertNoStrayProcessesLeft(self, grep_string: str) -> None:
        """
        Assert that there are no stray / zombie processes left with the provided command line
        string.
        """
        exit_code, stdout, stderr, timed_out = run_command(
            cmd="ps aux | grep %s | grep -v grep" % (quote_unix(grep_string)),
            shell=True,
        )

        if stdout.strip() != b"" and stderr.strip() != b"":
            raise AssertionError(
                "Expected no stray processes, but found Some. stdout: %s, stderr: %s"
                % (stdout, stderr)
            )

        Assert that there are no stray / zombie processes left with the provided command line
        string.
        
st2common/tests/integration/test_util_green.py