tests/heredoctest.py

sharesafe: add functionality to automatically downgrade shares

Reasoning is same as previous patch which adds automatic upgrade support.

Downgrade is required as if automatic upgrade is enabled, all shares upgrade and
then source repository downgrades, shares won't work. We need to downgrade them.

Differential Revision: https://phab.mercurial-scm.org/D9680

from __future__ import absolute_import, print_function

import sys


def flush():
    sys.stdout.flush()
    sys.stderr.flush()


globalvars = {}
lines = sys.stdin.readlines()
while lines:
    l = lines.pop(0)
    if l.startswith('SALT'):
        print(l[:-1])
    elif l.startswith('>>> '):
        snippet = l[4:]
        while lines and lines[0].startswith('... '):
            l = lines.pop(0)
            snippet += l[4:]
        c = compile(snippet, '<heredoc>', 'single')
        try:
            flush()
            exec(c, globalvars)
            flush()
        except Exception as inst:
            flush()
            print(repr(inst))