tests/test-encoding-func.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

import unittest

from mercurial import (
    encoding,
)

class IsasciistrTest(unittest.TestCase):
    asciistrs = [
        b'a',
        b'ab',
        b'abc',
        b'abcd',
        b'abcde',
        b'abcdefghi',
        b'abcd\0fghi',
    ]

    def testascii(self):
        for s in self.asciistrs:
            self.assertTrue(encoding.isasciistr(s))

    def testnonasciichar(self):
        for s in self.asciistrs:
            for i in range(len(s)):
                t = bytearray(s)
                t[i] |= 0x80
                self.assertFalse(encoding.isasciistr(bytes(t)))

class LocalEncodingTest(unittest.TestCase):
    def testasciifastpath(self):
        s = b'\0' * 100
        self.assertTrue(s is encoding.tolocal(s))
        self.assertTrue(s is encoding.fromlocal(s))

class Utf8bEncodingTest(unittest.TestCase):
    def testasciifastpath(self):
        s = b'\0' * 100
        self.assertTrue(s is encoding.toutf8b(s))
        self.assertTrue(s is encoding.fromutf8b(s))

if __name__ == '__main__':
    import silenttestrunner
    silenttestrunner.main(__name__)