tests/test-sshserver.py

tests: add low-level SSH protocol tests

We don't really have good low-level tests for the behavior of the SSH
wire protocol. This commit attempts to establish some.

The added tests consist of a mixture of starting a server
with `hg serve --stdio` and sending bytes to it and using
`hg debugpeer` to go through the official client code. Having
insight into what raw bytes are exchanged as well as what the peer
does is useful.

We also introduce a test extension for modifying the behavior of
the SSH server and peer. For example, we change the server to
not recognize the "hello" command, simulating behavior of <0.9.1
servers.

These tests are generally useful to have. But the impetus for creating
them now is they will be needed for verifying behavior of old clients
and servers when a new SSH protocol is introduced.

Differential Revision: https://phab.mercurial-scm.org/D2026

# no-check-commit because of serve_forever()

from __future__ import absolute_import, print_function

import io
import unittest

import silenttestrunner

from mercurial import (
    util,
    wireproto,
    wireprotoserver,
)

class SSHServerGetArgsTests(unittest.TestCase):
    def testparseknown(self):
        tests = [
            ('* 0\nnodes 0\n', ['', {}]),
            ('* 0\nnodes 40\n1111111111111111111111111111111111111111\n',
             ['1111111111111111111111111111111111111111', {}]),
        ]
        for input, expected in tests:
            self.assertparse('known', input, expected)

    def assertparse(self, cmd, input, expected):
        server = mockserver(input)
        _func, spec = wireproto.commands[cmd]
        self.assertEqual(server.getargs(spec), expected)

def mockserver(inbytes):
    ui = mockui(inbytes)
    repo = mockrepo(ui)
    return wireprotoserver.sshserver(ui, repo)

class mockrepo(object):
    def __init__(self, ui):
        self.ui = ui

class mockui(object):
    def __init__(self, inbytes):
        self.fin = io.BytesIO(inbytes)
        self.fout = io.BytesIO()
        self.ferr = io.BytesIO()

if __name__ == '__main__':
    # Don't call into msvcrt to set BytesIO to binary mode
    util.setbinary = lambda fp: True
    silenttestrunner.main(__name__)