tests/test-demandimport.py

basectx: add an empty class that will be used as a parent of all contexts

At the moment, there is no simple way to check if an object is a context
because there is no common parent class. If there were, we could use
'isinstance' everywhere. Simply having memctx inherit from workingctx or
changectx would allow the use of 'isinstance' but that could lead to some
confusing situations of reading the code since we have three distinct concepts
of a context:

- changectx represents a changeset *already* in the repo, and is therefore immutable
- workingctx represents changes on disk in the working directory
- memctx represents changes solely in memory which may or may not be on disk

Therefore, I propose refactoring context.py to have all three contexts inherit
from a parent class 'basectx'.

from mercurial import demandimport
demandimport.enable()

import re

rsub = re.sub
def f(obj):
    l = repr(obj)
    l = rsub("0x[0-9a-fA-F]+", "0x?", l)
    l = rsub("from '.*'", "from '?'", l)
    l = rsub("'<[a-z]*>'", "'<whatever>'", l)
    return l

import os

print "os =", f(os)
print "os.system =", f(os.system)
print "os =", f(os)

from mercurial import util

print "util =", f(util)
print "util.system =", f(util.system)
print "util =", f(util)
print "util.system =", f(util.system)

import re as fred
print "fred =", f(fred)

import sys as re
print "re =", f(re)

print "fred =", f(fred)
print "fred.sub =", f(fred.sub)
print "fred =", f(fred)

print "re =", f(re)
print "re.stderr =", f(re.stderr)
print "re =", f(re)