tests/test-check-interfaces.py

sshpeer: defer pipe buffering and stderr sidechannel binding

The doublepipe and bufferedinputpipe types facilitate polling
multiple pipes without blocking and for automatically forwarding
output from the SSH server's stderr pipe to the ui as "remote: "
output. This all happens automatically and callers don't need
to worry about reading from multiple pipes.

An upcoming change to version 2 of the SSH wire protocol will
eliminate the use of stderr and move side-channel output into
the "main" pipe. The SSH wire protocol will use a pair of
unidirectional pipes - just like the HTTP protocol. In this
future world, the doublepipe primitive isn't necessary because
the stderr pipe won't be used.

To prepare for eventually not using doublepipe, we delay the
construction of this primitive from immediately after
connection establishment to inside construction of the peer
instance. The handshake occurs between these two events. So
we had to teach the handshake code to read from stderr so
any stderr output from the server is still attended to early in
the connection lifetime.

Differential Revision: https://phab.mercurial-scm.org/D2383

# Test that certain objects conform to well-defined interfaces.

from __future__ import absolute_import, print_function

from mercurial import (
    bundlerepo,
    httppeer,
    localrepo,
    sshpeer,
    statichttprepo,
    ui as uimod,
    unionrepo,
)

def checkobject(o):
    """Verify a constructed object conforms to interface rules.

    An object must have __abstractmethods__ defined.

    All "public" attributes of the object (attributes not prefixed with
    an underscore) must be in __abstractmethods__ or appear on a base class
    with __abstractmethods__.
    """
    name = o.__class__.__name__

    allowed = set()
    for cls in o.__class__.__mro__:
        if not getattr(cls, '__abstractmethods__', set()):
            continue

        allowed |= cls.__abstractmethods__
        allowed |= {a for a in dir(cls) if not a.startswith('_')}

    if not allowed:
        print('%s does not have abstract methods' % name)
        return

    public = {a for a in dir(o) if not a.startswith('_')}

    for attr in sorted(public - allowed):
        print('public attributes not in abstract interface: %s.%s' % (
            name, attr))

# Facilitates testing localpeer.
class dummyrepo(object):
    def __init__(self):
        self.ui = uimod.ui()
    def filtered(self, name):
        pass
    def _restrictcapabilities(self, caps):
        pass

# Facilitates testing sshpeer without requiring an SSH server.
class badpeer(httppeer.httppeer):
    def __init__(self):
        super(badpeer, self).__init__(uimod.ui(), 'http://localhost')
        self.badattribute = True

    def badmethod(self):
        pass

class dummypipe(object):
    def close(self):
        pass

def main():
    ui = uimod.ui()

    checkobject(badpeer())
    checkobject(httppeer.httppeer(ui, 'http://localhost'))
    checkobject(localrepo.localpeer(dummyrepo()))
    checkobject(sshpeer.sshv1peer(ui, 'ssh://localhost/foo', None, dummypipe(),
                                  dummypipe(), None, None))
    checkobject(sshpeer.sshv2peer(ui, 'ssh://localhost/foo', None, dummypipe(),
                                  dummypipe(), None, None))
    checkobject(bundlerepo.bundlepeer(dummyrepo()))
    checkobject(statichttprepo.statichttppeer(dummyrepo()))
    checkobject(unionrepo.unionpeer(dummyrepo()))

main()