demandimport: allow extensions to import own modules by absolute name

Before this patch, python modules of each extensions can't import
another one in own extension by absolute name, because root modules of
each extensions are loaded with "hgext_" prefix.

For example, "import extroot.bar" in "extroot/foo.py" of "extroot"
extension fails, even though "import bar" in it succeeds.

Installing extensions into site-packages of python library path can
avoid this problem, but this solution is not reasonable in some cases:
using binary package of Mercurial on Windows, for example.

This patch retries to import with "hgext_" prefix after ImportError,
if the module in the extension may try to import another one in own
extension.

This patch doesn't change some "_import()"/"_origimport()" invocations
below, because ordinary extensions shouldn't cause such invocations.

    - invocation of "_import()" when root module imports sub-module by
      absolute path without "fromlist"

      for example, "import a.b" in "a.__init__.py".

      extensions are loaded with "hgext_" prefix, and this causes
      execution of another (= fixed by this patch) code path.

    - invocation of "_origimport()" when "level != -1" with "fromlist"

      for example, importing after "from __future__ import
      absolute_import" (level == 0), or "from . import b" or "from .a
      import b" (0 < level),

      for portability between python versions and environments,
      extensions shouldn't cause "level != -1".

mercurial/demandimport.py

@@ -1,156 +1,171
 # demandimport.py - global demand-loading of modules for Mercurial
 #
 # Copyright 2006, 2007 Matt Mackall <[e-mail]>
 #
 # This software may be used and distributed according to the terms of the
 # GNU General Public License version 2 or any later version.
 
 '''
 demandimport - automatic demandloading of modules
 
 To enable this module, do:
 
   import demandimport; demandimport.enable()
 
 Imports of the following forms will be demand-loaded:
 
   import a, b.c
   import a.b as c
   from a import b,c # a will be loaded immediately
 
 These imports will not be delayed:
 
   from a import *
   b = __import__(a)
 '''
 
 import __builtin__
 _origimport = __import__
 
 nothing = object()
 
 try:
     _origimport(__builtin__.__name__, {}, {}, None, -1)
 except TypeError: # no level argument
     def _import(name, globals, locals, fromlist, level):
         "call _origimport with no level argument"
         return _origimport(name, globals, locals, fromlist)
 else:
     _import = _origimport
 
+def _hgextimport(importfunc, name, globals, *args):
+    try:
+        return importfunc(name, globals, *args)
+    except ImportError:
+        if not globals:
+            raise
+        # extensions are loaded with "hgext_" prefix
+        hgextname = 'hgext_%s' % name
+        nameroot = hgextname.split('.', 1)[0]
+        contextroot = globals.get('__name__', '').split('.', 1)[0]
+        if nameroot != contextroot:
+            raise
+        # retry to import with "hgext_" prefix
+        return importfunc(hgextname, globals, *args)
+
 class _demandmod(object):
     """module demand-loader and proxy"""
     def __init__(self, name, globals, locals, level=-1):
         if '.' in name:
             head, rest = name.split('.', 1)
             after = [rest]
         else:
             head = name
             after = []
         object.__setattr__(self, "_data",
                            (head, globals, locals, after, level))
         object.__setattr__(self, "_module", None)
     def _extend(self, name):
         """add to the list of submodules to load"""
         self._data[3].append(name)
     def _load(self):
         if not self._module:
             head, globals, locals, after, level = self._data
-            mod = _import(head, globals, locals, None, level)
+            mod = _hgextimport(_import, head, globals, locals, None, level)
             # load submodules
             def subload(mod, p):
                 h, t = p, None
                 if '.' in p:
                     h, t = p.split('.', 1)
                 if getattr(mod, h, nothing) is nothing:
                     setattr(mod, h, _demandmod(p, mod.__dict__, mod.__dict__))
                 elif t:
                     subload(getattr(mod, h), t)
 
             for x in after:
                 subload(mod, x)
 
             # are we in the locals dictionary still?
             if locals and locals.get(head) == self:
                 locals[head] = mod
             object.__setattr__(self, "_module", mod)
 
     def __repr__(self):
         if self._module:
             return "<proxied module '%s'>" % self._data[0]
         return "<unloaded module '%s'>" % self._data[0]
     def __call__(self, *args, **kwargs):
         raise TypeError("%s object is not callable" % repr(self))
     def __getattribute__(self, attr):
         if attr in ('_data', '_extend', '_load', '_module'):
             return object.__getattribute__(self, attr)
         self._load()
         return getattr(self._module, attr)
     def __setattr__(self, attr, val):
         self._load()
         setattr(self._module, attr, val)
 
 def _demandimport(name, globals=None, locals=None, fromlist=None, level=-1):
     if not locals or name in ignore or fromlist == ('*',):
         # these cases we can't really delay
-        return _import(name, globals, locals, fromlist, level)
+        return _hgextimport(_import, name, globals, locals, fromlist, level)
     elif not fromlist:
         # import a [as b]
         if '.' in name: # a.b
             base, rest = name.split('.', 1)
             # email.__init__ loading email.mime
             if globals and globals.get('__name__', None) == base:
                 return _import(name, globals, locals, fromlist, level)
             # if a is already demand-loaded, add b to its submodule list
             if base in locals:
                 if isinstance(locals[base], _demandmod):
                     locals[base]._extend(rest)
                 return locals[base]
         return _demandmod(name, globals, locals, level)
     else:
         if level != -1:
             # from . import b,c,d or from .a import b,c,d
             return _origimport(name, globals, locals, fromlist, level)
         # from a import b,c,d
-        mod = _origimport(name, globals, locals)
+        mod = _hgextimport(_origimport, name, globals, locals)
         # recurse down the module chain
         for comp in name.split('.')[1:]:
             if getattr(mod, comp, nothing) is nothing:
                 setattr(mod, comp, _demandmod(comp, mod.__dict__, mod.__dict__))
             mod = getattr(mod, comp)
         for x in fromlist:
             # set requested submodules for demand load
             if getattr(mod, x, nothing) is nothing:
                 setattr(mod, x, _demandmod(x, mod.__dict__, locals))
         return mod
 
 ignore = [
     '_hashlib',
     '_xmlplus',
     'fcntl',
     'win32com.gen_py',
     '_winreg', # 2.7 mimetypes needs immediate ImportError
     'pythoncom',
     # imported by tarfile, not available under Windows
     'pwd',
     'grp',
     # imported by profile, itself imported by hotshot.stats,
     # not available under Windows
     'resource',
     # this trips up many extension authors
     'gtk',
     # setuptools' pkg_resources.py expects "from __main__ import x" to
     # raise ImportError if x not defined
     '__main__',
     '_ssl', # conditional imports in the stdlib, issue1964
     'rfc822',
     'mimetools',
     ]
 
 def enable():
     "enable global demand-loading of modules"
     __builtin__.__import__ = _demandimport
 
 def disable():
     "disable global demand-loading of modules"
     __builtin__.__import__ = _origimport

tests/test-extension.t

@@ -1,749 +1,840
 Test basic extension support
 
   $ cat > foobar.py <<EOF
   > import os
   > from mercurial import commands
   > 
   > def uisetup(ui):
   >     ui.write("uisetup called\\n")
   > 
   > def reposetup(ui, repo):
   >     ui.write("reposetup called for %s\\n" % os.path.basename(repo.root))
   >     ui.write("ui %s= repo.ui\\n" % (ui == repo.ui and "=" or "!"))
   > 
   > def foo(ui, *args, **kwargs):
   >     ui.write("Foo\\n")
   > 
   > def bar(ui, *args, **kwargs):
   >     ui.write("Bar\\n")
   > 
   > cmdtable = {
   >    "foo": (foo, [], "hg foo"),
   >    "bar": (bar, [], "hg bar"),
   > }
   > 
   > commands.norepo += ' bar'
   > EOF
   $ abspath=`pwd`/foobar.py
 
   $ mkdir barfoo
   $ cp foobar.py barfoo/__init__.py
   $ barfoopath=`pwd`/barfoo
 
   $ hg init a
   $ cd a
   $ echo foo > file
   $ hg add file
   $ hg commit -m 'add file'
 
   $ echo '[extensions]' >> $HGRCPATH
   $ echo "foobar = $abspath" >> $HGRCPATH
   $ hg foo
   uisetup called
   reposetup called for a
   ui == repo.ui
   Foo
 
   $ cd ..
   $ hg clone a b
   uisetup called
   reposetup called for a
   ui == repo.ui
   reposetup called for b
   ui == repo.ui
   updating to branch default
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved
 
   $ hg bar
   uisetup called
   Bar
   $ echo 'foobar = !' >> $HGRCPATH
 
 module/__init__.py-style
 
   $ echo "barfoo = $barfoopath" >> $HGRCPATH
   $ cd a
   $ hg foo
   uisetup called
   reposetup called for a
   ui == repo.ui
   Foo
   $ echo 'barfoo = !' >> $HGRCPATH
 
 Check that extensions are loaded in phases:
 
   $ cat > foo.py <<EOF
   > import os
   > name = os.path.basename(__file__).rsplit('.', 1)[0]
   > print "1) %s imported" % name
   > def uisetup(ui):
   >     print "2) %s uisetup" % name
   > def extsetup():
   >     print "3) %s extsetup" % name
   > def reposetup(ui, repo):
   >    print "4) %s reposetup" % name
   > EOF
 
   $ cp foo.py bar.py
   $ echo 'foo = foo.py' >> $HGRCPATH
   $ echo 'bar = bar.py' >> $HGRCPATH
 
 Command with no output, we just want to see the extensions loaded:
 
   $ hg paths
   1) foo imported
   1) bar imported
   2) foo uisetup
   2) bar uisetup
   3) foo extsetup
   3) bar extsetup
   4) foo reposetup
   4) bar reposetup
 
 Check hgweb's load order:
 
   $ cat > hgweb.cgi <<EOF
   > #!/usr/bin/env python
   > from mercurial import demandimport; demandimport.enable()
   > from mercurial.hgweb import hgweb
   > from mercurial.hgweb import wsgicgi
   > 
   > application = hgweb('.', 'test repo')
   > wsgicgi.launch(application)
   > EOF
 
   $ REQUEST_METHOD='GET' PATH_INFO='/' SCRIPT_NAME='' QUERY_STRING='' \
   >    SERVER_PORT='80' SERVER_NAME='localhost' python hgweb.cgi \
   >    | grep '^[0-9]) ' # ignores HTML output
   1) foo imported
   1) bar imported
   2) foo uisetup
   2) bar uisetup
   3) foo extsetup
   3) bar extsetup
   4) foo reposetup
   4) bar reposetup
   4) foo reposetup
   4) bar reposetup
 
   $ echo 'foo = !' >> $HGRCPATH
   $ echo 'bar = !' >> $HGRCPATH
 
 Check "from __future__ import absolute_import" support for external libraries
 
   $ mkdir $TESTTMP/libroot
   $ echo "s = 'libroot/ambig.py'" > $TESTTMP/libroot/ambig.py
   $ mkdir $TESTTMP/libroot/mod
   $ touch $TESTTMP/libroot/mod/__init__.py
   $ echo "s = 'libroot/mod/ambig.py'" > $TESTTMP/libroot/mod/ambig.py
 
 #if absimport
   $ cat > $TESTTMP/libroot/mod/ambigabs.py <<EOF
   > from __future__ import absolute_import
   > import ambig # should load "libroot/ambig.py"
   > s = ambig.s
   > EOF
   $ cat > loadabs.py <<EOF
   > import mod.ambigabs as ambigabs
   > def extsetup():
   >     print 'ambigabs.s=%s' % ambigabs.s
   > EOF
   $ (PYTHONPATH=$PYTHONPATH:$TESTTMP/libroot; hg --config extensions.loadabs=loadabs.py root)
   ambigabs.s=libroot/ambig.py
   $TESTTMP/a
 #endif
 
 #if no-py3k
   $ cat > $TESTTMP/libroot/mod/ambigrel.py <<EOF
   > import ambig # should load "libroot/mod/ambig.py"
   > s = ambig.s
   > EOF
   $ cat > loadrel.py <<EOF
   > import mod.ambigrel as ambigrel
   > def extsetup():
   >     print 'ambigrel.s=%s' % ambigrel.s
   > EOF
   $ (PYTHONPATH=$PYTHONPATH:$TESTTMP/libroot; hg --config extensions.loadrel=loadrel.py root)
   ambigrel.s=libroot/mod/ambig.py
   $TESTTMP/a
 #endif
 
+Check absolute/relative import of extension specific modules
+
+  $ mkdir $TESTTMP/extroot
+  $ cat > $TESTTMP/extroot/bar.py <<EOF
+  > s = 'this is extroot.bar'
+  > EOF
+  $ mkdir $TESTTMP/extroot/sub1
+  $ cat > $TESTTMP/extroot/sub1/__init__.py <<EOF
+  > s = 'this is extroot.sub1.__init__'
+  > EOF
+  $ cat > $TESTTMP/extroot/sub1/baz.py <<EOF
+  > s = 'this is extroot.sub1.baz'
+  > EOF
+  $ cat > $TESTTMP/extroot/__init__.py <<EOF
+  > s = 'this is extroot.__init__'
+  > import foo
+  > def extsetup(ui):
+  >     ui.write('(extroot) ', foo.func(), '\n')
+  > EOF
+
+  $ cat > $TESTTMP/extroot/foo.py <<EOF
+  > # test absolute import
+  > buf = []
+  > def func():
+  >     # "not locals" case
+  >     import extroot.bar
+  >     buf.append('import extroot.bar in func(): %s' % extroot.bar.s)
+  > 
+  >     return '\n(extroot) '.join(buf)
+  > 
+  > # "fromlist == ('*',)" case
+  > from extroot.bar import *
+  > buf.append('from extroot.bar import *: %s' % s)
+  > 
+  > # "not fromlist" and "if '.' in name" case
+  > import extroot.sub1.baz
+  > buf.append('import extroot.sub1.baz: %s' % extroot.sub1.baz.s)
+  > 
+  > # "not fromlist" and NOT "if '.' in name" case
+  > import extroot
+  > buf.append('import extroot: %s' % extroot.s)
+  > 
+  > # NOT "not fromlist" and NOT "level != -1" case
+  > from extroot.bar import s
+  > buf.append('from extroot.bar import s: %s' % s)
+  > EOF
+  $ hg --config extensions.extroot=$TESTTMP/extroot root
+  (extroot) from extroot.bar import *: this is extroot.bar
+  (extroot) import extroot.sub1.baz: this is extroot.sub1.baz
+  (extroot) import extroot: this is extroot.__init__
+  (extroot) from extroot.bar import s: this is extroot.bar
+  (extroot) import extroot.bar in func(): this is extroot.bar
+  $TESTTMP/a
+
+#if no-py3k
+  $ rm -f $TESTTMP/extroot/foo.*
+  $ cat > $TESTTMP/extroot/foo.py <<EOF
+  > # test relative import
+  > buf = []
+  > def func():
+  >     # "not locals" case
+  >     import bar
+  >     buf.append('import bar in func(): %s' % bar.s)
+  > 
+  >     return '\n(extroot) '.join(buf)
+  > 
+  > # "fromlist == ('*',)" case
+  > from bar import *
+  > buf.append('from bar import *: %s' % s)
+  > 
+  > # "not fromlist" and "if '.' in name" case
+  > import sub1.baz
+  > buf.append('import sub1.baz: %s' % sub1.baz.s)
+  > 
+  > # "not fromlist" and NOT "if '.' in name" case
+  > import sub1
+  > buf.append('import sub1: %s' % sub1.s)
+  > 
+  > # NOT "not fromlist" and NOT "level != -1" case
+  > from bar import s
+  > buf.append('from bar import s: %s' % s)
+  > EOF
+  $ hg --config extensions.extroot=$TESTTMP/extroot root
+  (extroot) from bar import *: this is extroot.bar
+  (extroot) import sub1.baz: this is extroot.sub1.baz
+  (extroot) import sub1: this is extroot.sub1.__init__
+  (extroot) from bar import s: this is extroot.bar
+  (extroot) import bar in func(): this is extroot.bar
+  $TESTTMP/a
+#endif
+
   $ cd ..
 
 hide outer repo
   $ hg init
 
   $ cat > empty.py <<EOF
   > '''empty cmdtable
   > '''
   > cmdtable = {}
   > EOF
   $ emptypath=`pwd`/empty.py
   $ echo "empty = $emptypath" >> $HGRCPATH
   $ hg help empty
   empty extension - empty cmdtable
   
   no commands defined
 
   $ echo 'empty = !' >> $HGRCPATH
 
   $ cat > debugextension.py <<EOF
   > '''only debugcommands
   > '''
   > def debugfoobar(ui, repo, *args, **opts):
   >     "yet another debug command"
   >     pass
   > 
   > def foo(ui, repo, *args, **opts):
   >     """yet another foo command
   > 
   >     This command has been DEPRECATED since forever.
   >     """
   >     pass
   > 
   > cmdtable = {
   >    "debugfoobar": (debugfoobar, (), "hg debugfoobar"),
   >    "foo": (foo, (), "hg foo")
   > }
   > EOF
   $ debugpath=`pwd`/debugextension.py
   $ echo "debugextension = $debugpath" >> $HGRCPATH
 
   $ hg help debugextension
   debugextension extension - only debugcommands
   
   no commands defined
 
   $ hg --verbose help debugextension
   debugextension extension - only debugcommands
   
   list of commands:
   
    foo           yet another foo command
   
   global options:
   
    -R --repository REPO   repository root directory or name of overlay bundle
                           file
       --cwd DIR           change working directory
    -y --noninteractive    do not prompt, automatically pick the first choice for
                           all prompts
    -q --quiet             suppress output
    -v --verbose           enable additional output
       --config CONFIG [+] set/override config option (use 'section.name=value')
       --debug             enable debugging output
       --debugger          start debugger
       --encoding ENCODE   set the charset encoding (default: ascii)
       --encodingmode MODE set the charset encoding mode (default: strict)
       --traceback         always print a traceback on exception
       --time              time how long the command takes
       --profile           print command execution profile
       --version           output version information and exit
    -h --help              display help and exit
       --hidden            consider hidden changesets
   
   [+] marked option can be specified multiple times
 
   $ hg --debug help debugextension
   debugextension extension - only debugcommands
   
   list of commands:
   
    debugfoobar   yet another debug command
    foo           yet another foo command
   
   global options:
   
    -R --repository REPO   repository root directory or name of overlay bundle
                           file
       --cwd DIR           change working directory
    -y --noninteractive    do not prompt, automatically pick the first choice for
                           all prompts
    -q --quiet             suppress output
    -v --verbose           enable additional output
       --config CONFIG [+] set/override config option (use 'section.name=value')
       --debug             enable debugging output
       --debugger          start debugger
       --encoding ENCODE   set the charset encoding (default: ascii)
       --encodingmode MODE set the charset encoding mode (default: strict)
       --traceback         always print a traceback on exception
       --time              time how long the command takes
       --profile           print command execution profile
       --version           output version information and exit
    -h --help              display help and exit
       --hidden            consider hidden changesets
   
   [+] marked option can be specified multiple times
   $ echo 'debugextension = !' >> $HGRCPATH
 
 Extension module help vs command help:
 
   $ echo 'extdiff =' >> $HGRCPATH
   $ hg help extdiff
   hg extdiff [OPT]... [FILE]...
   
   use external program to diff repository (or selected files)
   
       Show differences between revisions for the specified files, using an
       external program. The default program used is diff, with default options
       "-Npru".
   
       To select a different program, use the -p/--program option. The program
       will be passed the names of two directories to compare. To pass additional
       options to the program, use -o/--option. These will be passed before the
       names of the directories to compare.
   
       When two revision arguments are given, then changes are shown between
       those revisions. If only one revision is specified then that revision is
       compared to the working directory, and, when no revisions are specified,
       the working directory files are compared to its parent.
   
   use "hg help -e extdiff" to show help for the extdiff extension
   
   options:
   
    -p --program CMD         comparison program to run
    -o --option OPT [+]      pass option to comparison program
    -r --rev REV [+]         revision
    -c --change REV          change made by revision
    -I --include PATTERN [+] include names matching the given patterns
    -X --exclude PATTERN [+] exclude names matching the given patterns
   
   [+] marked option can be specified multiple times
   
   use "hg -v help extdiff" to show the global options
 
   $ hg help --extension extdiff
   extdiff extension - command to allow external programs to compare revisions
   
   The extdiff Mercurial extension allows you to use external programs to compare
   revisions, or revision with working directory. The external diff programs are
   called with a configurable set of options and two non-option arguments: paths
   to directories containing snapshots of files to compare.
   
   The extdiff extension also allows you to configure new diff commands, so you
   do not need to type "hg extdiff -p kdiff3" always.
   
     [extdiff]
     # add new command that runs GNU diff(1) in 'context diff' mode
     cdiff = gdiff -Nprc5
     ## or the old way:
     #cmd.cdiff = gdiff
     #opts.cdiff = -Nprc5
   
     # add new command called vdiff, runs kdiff3
     vdiff = kdiff3
   
     # add new command called meld, runs meld (no need to name twice)
     meld =
   
     # add new command called vimdiff, runs gvimdiff with DirDiff plugin
     # (see http://www.vim.org/scripts/script.php?script_id=102) Non
     # English user, be sure to put "let g:DirDiffDynamicDiffText = 1" in
     # your .vimrc
     vimdiff = gvim -f "+next" \
               "+execute 'DirDiff' fnameescape(argv(0)) fnameescape(argv(1))"
   
   Tool arguments can include variables that are expanded at runtime:
   
     $parent1, $plabel1 - filename, descriptive label of first parent
     $child,   $clabel  - filename, descriptive label of child revision
     $parent2, $plabel2 - filename, descriptive label of second parent
     $root              - repository root
     $parent is an alias for $parent1.
   
   The extdiff extension will look in your [diff-tools] and [merge-tools]
   sections for diff tool arguments, when none are specified in [extdiff].
   
     [extdiff]
     kdiff3 =
   
     [diff-tools]
     kdiff3.diffargs=--L1 '$plabel1' --L2 '$clabel' $parent $child
   
   You can use -I/-X and list of file or directory names like normal "hg diff"
   command. The extdiff extension makes snapshots of only needed files, so
   running the external diff program will actually be pretty fast (at least
   faster than having to compare the entire tree).
   
   list of commands:
   
    extdiff       use external program to diff repository (or selected files)
   
   use "hg -v help extdiff" to show builtin aliases and global options
 
   $ echo 'extdiff = !' >> $HGRCPATH
 
 Test help topic with same name as extension
 
   $ cat > multirevs.py <<EOF
   > from mercurial import commands
   > """multirevs extension
   > Big multi-line module docstring."""
   > def multirevs(ui, repo, arg, *args, **opts):
   >     """multirevs command"""
   >     pass
   > cmdtable = {
   >    "multirevs": (multirevs, [], 'ARG')
   > }
   > commands.norepo += ' multirevs'
   > EOF
   $ echo "multirevs = multirevs.py" >> $HGRCPATH
 
   $ hg help multirevs
   Specifying Multiple Revisions
   """""""""""""""""""""""""""""
   
       When Mercurial accepts more than one revision, they may be specified
       individually, or provided as a topologically continuous range, separated
       by the ":" character.
   
       The syntax of range notation is [BEGIN]:[END], where BEGIN and END are
       revision identifiers. Both BEGIN and END are optional. If BEGIN is not
       specified, it defaults to revision number 0. If END is not specified, it
       defaults to the tip. The range ":" thus means "all revisions".
   
       If BEGIN is greater than END, revisions are treated in reverse order.
   
       A range acts as a closed interval. This means that a range of 3:5 gives 3,
       4 and 5. Similarly, a range of 9:6 gives 9, 8, 7, and 6.
   
   use "hg help -c multirevs" to see help for the multirevs command
 
   $ hg help -c multirevs
   hg multirevs ARG
   
   multirevs command
   
   use "hg -v help multirevs" to show the global options
 
   $ hg multirevs
   hg multirevs: invalid arguments
   hg multirevs ARG
   
   multirevs command
   
   use "hg help multirevs" to show the full help text
   [255]
 
   $ echo "multirevs = !" >> $HGRCPATH
 
 Issue811: Problem loading extensions twice (by site and by user)
 
   $ debugpath=`pwd`/debugissue811.py
   $ cat > debugissue811.py <<EOF
   > '''show all loaded extensions
   > '''
   > from mercurial import extensions, commands
   > 
   > def debugextensions(ui):
   >     "yet another debug command"
   >     ui.write("%s\n" % '\n'.join([x for x, y in extensions.extensions()]))
   > 
   > cmdtable = {"debugextensions": (debugextensions, (), "hg debugextensions")}
   > commands.norepo += " debugextensions"
   > EOF
   $ echo "debugissue811 = $debugpath" >> $HGRCPATH
   $ echo "mq=" >> $HGRCPATH
   $ echo "strip=" >> $HGRCPATH
   $ echo "hgext.mq=" >> $HGRCPATH
   $ echo "hgext/mq=" >> $HGRCPATH
 
 Show extensions:
 (note that mq force load strip, also checking it's not loaded twice)
 
   $ hg debugextensions
   debugissue811
   strip
   mq
 
 Disabled extension commands:
 
   $ ORGHGRCPATH=$HGRCPATH
   $ HGRCPATH=
   $ export HGRCPATH
   $ hg help email
   'email' is provided by the following extension:
   
       patchbomb     command to send changesets as (a series of) patch emails
   
   use "hg help extensions" for information on enabling extensions
   $ hg qdel
   hg: unknown command 'qdel'
   'qdelete' is provided by the following extension:
   
       mq            manage a stack of patches
   
   use "hg help extensions" for information on enabling extensions
   [255]
   $ hg churn
   hg: unknown command 'churn'
   'churn' is provided by the following extension:
   
       churn         command to display statistics about repository history
   
   use "hg help extensions" for information on enabling extensions
   [255]
 
 Disabled extensions:
 
   $ hg help churn
   churn extension - command to display statistics about repository history
   
   use "hg help extensions" for information on enabling extensions
   $ hg help patchbomb
   patchbomb extension - command to send changesets as (a series of) patch emails
   
   use "hg help extensions" for information on enabling extensions
 
 Broken disabled extension and command:
 
   $ mkdir hgext
   $ echo > hgext/__init__.py
   $ cat > hgext/broken.py <<EOF
   > "broken extension'
   > EOF
   $ cat > path.py <<EOF
   > import os, sys
   > sys.path.insert(0, os.environ['HGEXTPATH'])
   > EOF
   $ HGEXTPATH=`pwd`
   $ export HGEXTPATH
 
   $ hg --config extensions.path=./path.py help broken
   broken extension - (no help text available)
   
   use "hg help extensions" for information on enabling extensions
 
   $ cat > hgext/forest.py <<EOF
   > cmdtable = None
   > EOF
   $ hg --config extensions.path=./path.py help foo > /dev/null
   warning: error finding commands in $TESTTMP/hgext/forest.py (glob)
   hg: unknown command 'foo'
   warning: error finding commands in $TESTTMP/hgext/forest.py (glob)
   [255]
 
   $ cat > throw.py <<EOF
   > from mercurial import cmdutil, commands
   > cmdtable = {}
   > command = cmdutil.command(cmdtable)
   > class Bogon(Exception): pass
   > 
   > @command('throw', [], 'hg throw')
   > def throw(ui, **opts):
   >     """throws an exception"""
   >     raise Bogon()
   > commands.norepo += " throw"
   > EOF
 No declared supported version, extension complains:
   $ hg --config extensions.throw=throw.py throw 2>&1 | egrep '^\*\*'
   ** Unknown exception encountered with possibly-broken third-party extension throw
   ** which supports versions unknown of Mercurial.
   ** Please disable throw and try your action again.
   ** If that fixes the bug please report it to the extension author.
   ** Python * (glob)
   ** Mercurial Distributed SCM * (glob)
   ** Extensions loaded: throw
 empty declaration of supported version, extension complains:
   $ echo "testedwith = ''" >> throw.py
   $ hg --config extensions.throw=throw.py throw 2>&1 | egrep '^\*\*'
   ** Unknown exception encountered with possibly-broken third-party extension throw
   ** which supports versions unknown of Mercurial.
   ** Please disable throw and try your action again.
   ** If that fixes the bug please report it to the extension author.
   ** Python * (glob)
   ** Mercurial Distributed SCM (*) (glob)
   ** Extensions loaded: throw
 If the extension specifies a buglink, show that:
   $ echo 'buglink = "http://example.com/bts"' >> throw.py
   $ rm -f throw.pyc throw.pyo
   $ hg --config extensions.throw=throw.py throw 2>&1 | egrep '^\*\*'
   ** Unknown exception encountered with possibly-broken third-party extension throw
   ** which supports versions unknown of Mercurial.
   ** Please disable throw and try your action again.
   ** If that fixes the bug please report it to http://example.com/bts
   ** Python * (glob)
   ** Mercurial Distributed SCM (*) (glob)
   ** Extensions loaded: throw
 If the extensions declare outdated versions, accuse the older extension first:
   $ echo "from mercurial import util" >> older.py
   $ echo "util.version = lambda:'2.2'" >> older.py
   $ echo "testedwith = '1.9.3'" >> older.py
   $ echo "testedwith = '2.1.1'" >> throw.py
   $ rm -f throw.pyc throw.pyo
   $ hg --config extensions.throw=throw.py --config extensions.older=older.py \
   >   throw 2>&1 | egrep '^\*\*'
   ** Unknown exception encountered with possibly-broken third-party extension older
   ** which supports versions 1.9.3 of Mercurial.
   ** Please disable older and try your action again.
   ** If that fixes the bug please report it to the extension author.
   ** Python * (glob)
   ** Mercurial Distributed SCM (version 2.2)
   ** Extensions loaded: throw, older
 One extension only tested with older, one only with newer versions:
   $ echo "util.version = lambda:'2.1.0'" >> older.py
   $ rm -f older.pyc older.pyo
   $ hg --config extensions.throw=throw.py --config extensions.older=older.py \
   >   throw 2>&1 | egrep '^\*\*'
   ** Unknown exception encountered with possibly-broken third-party extension older
   ** which supports versions 1.9.3 of Mercurial.
   ** Please disable older and try your action again.
   ** If that fixes the bug please report it to the extension author.
   ** Python * (glob)
   ** Mercurial Distributed SCM (version 2.1.0)
   ** Extensions loaded: throw, older
 Older extension is tested with current version, the other only with newer:
   $ echo "util.version = lambda:'1.9.3'" >> older.py
   $ rm -f older.pyc older.pyo
   $ hg --config extensions.throw=throw.py --config extensions.older=older.py \
   >   throw 2>&1 | egrep '^\*\*'
   ** Unknown exception encountered with possibly-broken third-party extension throw
   ** which supports versions 2.1.1 of Mercurial.
   ** Please disable throw and try your action again.
   ** If that fixes the bug please report it to http://example.com/bts
   ** Python * (glob)
   ** Mercurial Distributed SCM (version 1.9.3)
   ** Extensions loaded: throw, older
 
 Declare the version as supporting this hg version, show regular bts link:
   $ hgver=`python -c 'from mercurial import util; print util.version().split("+")[0]'`
   $ echo 'testedwith = """'"$hgver"'"""' >> throw.py
   $ rm -f throw.pyc throw.pyo
   $ hg --config extensions.throw=throw.py throw 2>&1 | egrep '^\*\*'
   ** unknown exception encountered, please report by visiting
   ** http://mercurial.selenic.com/wiki/BugTracker
   ** Python * (glob)
   ** Mercurial Distributed SCM (*) (glob)
   ** Extensions loaded: throw
 
 Restore HGRCPATH
 
   $ HGRCPATH=$ORGHGRCPATH
   $ export HGRCPATH
 
 Commands handling multiple repositories at a time should invoke only
 "reposetup()" of extensions enabling in the target repository.
 
   $ mkdir reposetup-test
   $ cd reposetup-test
 
   $ cat > $TESTTMP/reposetuptest.py <<EOF
   > from mercurial import extensions
   > def reposetup(ui, repo):
   >     ui.write('reposetup() for %s\n' % (repo.root))
   > EOF
   $ hg init src
   $ echo a > src/a
   $ hg -R src commit -Am '#0 at src/a'
   adding a
   $ echo '[extensions]' >> src/.hg/hgrc
   $ echo '# enable extension locally' >> src/.hg/hgrc
   $ echo "reposetuptest = $TESTTMP/reposetuptest.py" >> src/.hg/hgrc
   $ hg -R src status
   reposetup() for $TESTTMP/reposetup-test/src
 
   $ hg clone -U src clone-dst1
   reposetup() for $TESTTMP/reposetup-test/src
   $ hg init push-dst1
   $ hg -q -R src push push-dst1
   reposetup() for $TESTTMP/reposetup-test/src
   $ hg init pull-src1
   $ hg -q -R pull-src1 pull src
   reposetup() for $TESTTMP/reposetup-test/src
 
   $ echo '[extensions]' >> $HGRCPATH
   $ echo '# disable extension globally and explicitly' >> $HGRCPATH
   $ echo 'reposetuptest = !' >> $HGRCPATH
   $ hg clone -U src clone-dst2
   reposetup() for $TESTTMP/reposetup-test/src
   $ hg init push-dst2
   $ hg -q -R src push push-dst2
   reposetup() for $TESTTMP/reposetup-test/src
   $ hg init pull-src2
   $ hg -q -R pull-src2 pull src
   reposetup() for $TESTTMP/reposetup-test/src
 
   $ echo '[extensions]' >> $HGRCPATH
   $ echo '# enable extension globally' >> $HGRCPATH
   $ echo "reposetuptest = $TESTTMP/reposetuptest.py" >> $HGRCPATH
   $ hg clone -U src clone-dst3
   reposetup() for $TESTTMP/reposetup-test/src
   reposetup() for $TESTTMP/reposetup-test/clone-dst3
   $ hg init push-dst3
   reposetup() for $TESTTMP/reposetup-test/push-dst3
   $ hg -q -R src push push-dst3
   reposetup() for $TESTTMP/reposetup-test/src
   reposetup() for $TESTTMP/reposetup-test/push-dst3
   $ hg init pull-src3
   reposetup() for $TESTTMP/reposetup-test/pull-src3
   $ hg -q -R pull-src3 pull src
   reposetup() for $TESTTMP/reposetup-test/pull-src3
   reposetup() for $TESTTMP/reposetup-test/src
 
   $ echo '[extensions]' >> src/.hg/hgrc
   $ echo '# disable extension locally' >> src/.hg/hgrc
   $ echo 'reposetuptest = !' >> src/.hg/hgrc
   $ hg clone -U src clone-dst4
   reposetup() for $TESTTMP/reposetup-test/clone-dst4
   $ hg init push-dst4
   reposetup() for $TESTTMP/reposetup-test/push-dst4
   $ hg -q -R src push push-dst4
   reposetup() for $TESTTMP/reposetup-test/push-dst4
   $ hg init pull-src4
   reposetup() for $TESTTMP/reposetup-test/pull-src4
   $ hg -q -R pull-src4 pull src
   reposetup() for $TESTTMP/reposetup-test/pull-src4
 
 disabling in command line overlays with all configuration
   $ hg --config extensions.reposetuptest=! clone -U src clone-dst5
   $ hg --config extensions.reposetuptest=! init push-dst5
   $ hg --config extensions.reposetuptest=! -q -R src push push-dst5
   $ hg --config extensions.reposetuptest=! init pull-src5
   $ hg --config extensions.reposetuptest=! -q -R pull-src5 pull src
 
   $ echo '[extensions]' >> $HGRCPATH
   $ echo '# disable extension globally and explicitly' >> $HGRCPATH
   $ echo 'reposetuptest = !' >> $HGRCPATH
   $ hg init parent
   $ hg init parent/sub1
   $ echo 1 > parent/sub1/1
   $ hg -R parent/sub1 commit -Am '#0 at parent/sub1'
   adding 1
   $ hg init parent/sub2
   $ hg init parent/sub2/sub21
   $ echo 21 > parent/sub2/sub21/21
   $ hg -R parent/sub2/sub21 commit -Am '#0 at parent/sub2/sub21'
   adding 21
   $ cat > parent/sub2/.hgsub <<EOF
   > sub21 = sub21
   > EOF
   $ hg -R parent/sub2 commit -Am '#0 at parent/sub2'
   adding .hgsub
   $ hg init parent/sub3
   $ echo 3 > parent/sub3/3
   $ hg -R parent/sub3 commit -Am '#0 at parent/sub3'
   adding 3
   $ cat > parent/.hgsub <<EOF
   > sub1 = sub1
   > sub2 = sub2
   > sub3 = sub3
   > EOF
   $ hg -R parent commit -Am '#0 at parent'
   adding .hgsub
   $ echo '[extensions]' >> parent/.hg/hgrc
   $ echo '# enable extension locally' >> parent/.hg/hgrc
   $ echo "reposetuptest = $TESTTMP/reposetuptest.py" >> parent/.hg/hgrc
   $ cp parent/.hg/hgrc parent/sub2/.hg/hgrc
   $ hg -R parent status -S -A
   reposetup() for $TESTTMP/reposetup-test/parent
   reposetup() for $TESTTMP/reposetup-test/parent/sub2
   C .hgsub
   C .hgsubstate
   C sub1/1
   C sub2/.hgsub
   C sub2/.hgsubstate
   C sub2/sub21/21
   C sub3/3
 
   $ cd ..