annotate tests/test-extension.t @ 20742:3681de20b0a7

parsers: fail fast if Python has wrong minor version (issue4110)

This change causes an informative ImportError to be raised when importing
the parsers extension module if the minor version of the currently-running
Python interpreter doesn't match that of the Python used when compiling
the extension module.

This change also exposes a parsers.versionerrortext constant in the
C implementation of the module.  Its presence can be used to determine
whether this behavior is present in a version of the module.  The value
of the constant is the leading text of the ImportError raised and is set
to "Python minor version mismatch".

Here is an example of what the new error looks like:

  Traceback (most recent call last):
    File "test.py", line 1, in <module>
      import mercurial.parsers
  ImportError: Python minor version mismatch: The Mercurial extension
  modules were compiled with Python 2.7.6, but Mercurial is currently using
  Python with sys.hexversion=33883888: Python 2.5.6
  (r256:88840, Nov 18 2012, 05:37:10)
  [GCC 4.2.1 Compatible Apple Clang 4.1 ((tags/Apple/clang-421.11.66))]
   at: /opt/local/Library/Frameworks/Python.framework/Versions/2.5/Resources/
    Python.app/Contents/MacOS/Python

The reason for raising an error in this scenario is that Python's C API
is known not to be compatible from minor version to minor version, even
if sys.api_version is the same.  See for example this Python bug report
about incompatibilities between 2.5 and 2.6+:

  http://bugs.python.org/issue8118

These incompatibilities can cause Mercurial to break in mysterious,
unforeseen ways.  For example, when Mercurial compiled with Python 2.7 was
run with 2.5, the following crash occurred when running "hg status":

  http://bz.selenic.com/show_bug.cgi?id=4110

After this crash was fixed, running with Python 2.5 no longer crashes, but
the following puzzling behavior still occurs:

    $ hg status
      ...
      File ".../mercurial/changelog.py", line 123, in __init__
        revlog.revlog.__init__(self, opener, "00changelog.i")
      File ".../mercurial/revlog.py", line 251, in __init__
        d = self._io.parseindex(i, self._inline)
      File ".../mercurial/revlog.py", line 158, in parseindex
        index, cache = parsers.parse_index2(data, inline)
    TypeError: data is not a string

which can be reproduced more simply with:

    import mercurial.parsers as parsers
    parsers.parse_index2("", True)

Both the crash and the TypeError occurred because the Python C API's
PyString_Check() returns the wrong value when the C header files from
Python 2.7 are run with Python 2.5.  This is an example of an
incompatibility of the sort mentioned in the Python bug report above.

Failing fast with an informative error message results in a better user
experience in cases like the above.  The information in the ImportError
also simplifies troubleshooting for those on Mercurial mailing lists, the
bug tracker, etc.

This patch only adds the version check to parsers.c, which is sufficient
to affect command-line commands like "hg status" and "hg summary".
An idea for a future improvement is to move the version-checking C code
to a more central location, and have it run when importing all
Mercurial extension modules and not just parsers.c.

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

#if windows
  $ PATHSEP=";"
#else
  $ PATHSEP=":"
#endif
  $ export PATHSEP

  $ 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=${PYTHONPATH}${PATHSEP}${TESTTMP}/libroot; hg --config extensions.loadabs=loadabs.py root)
  ambigabs.s=libroot/ambig.py
  $TESTTMP/a (glob)
#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=${PYTHONPATH}${PATHSEP}${TESTTMP}/libroot; hg --config extensions.loadrel=loadrel.py root)
  ambigrel.s=libroot/mod/ambig.py
  $TESTTMP/a (glob)
#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 (glob)

#if no-py3k
  $ rm "$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 (glob)
#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 (glob)

  $ hg clone -U src clone-dst1
  reposetup() for $TESTTMP/reposetup-test/src (glob)
  $ hg init push-dst1
  $ hg -q -R src push push-dst1
  reposetup() for $TESTTMP/reposetup-test/src (glob)
  $ hg init pull-src1
  $ hg -q -R pull-src1 pull src
  reposetup() for $TESTTMP/reposetup-test/src (glob)

  $ 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 (glob)
  $ hg init push-dst2
  $ hg -q -R src push push-dst2
  reposetup() for $TESTTMP/reposetup-test/src (glob)
  $ hg init pull-src2
  $ hg -q -R pull-src2 pull src
  reposetup() for $TESTTMP/reposetup-test/src (glob)

  $ 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 (glob)
  reposetup() for $TESTTMP/reposetup-test/clone-dst3 (glob)
  $ hg init push-dst3
  reposetup() for $TESTTMP/reposetup-test/push-dst3 (glob)
  $ hg -q -R src push push-dst3
  reposetup() for $TESTTMP/reposetup-test/src (glob)
  reposetup() for $TESTTMP/reposetup-test/push-dst3 (glob)
  $ hg init pull-src3
  reposetup() for $TESTTMP/reposetup-test/pull-src3 (glob)
  $ hg -q -R pull-src3 pull src
  reposetup() for $TESTTMP/reposetup-test/pull-src3 (glob)
  reposetup() for $TESTTMP/reposetup-test/src (glob)

  $ 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 (glob)
  $ hg init push-dst4
  reposetup() for $TESTTMP/reposetup-test/push-dst4 (glob)
  $ hg -q -R src push push-dst4
  reposetup() for $TESTTMP/reposetup-test/push-dst4 (glob)
  $ hg init pull-src4
  reposetup() for $TESTTMP/reposetup-test/pull-src4 (glob)
  $ hg -q -R pull-src4 pull src
  reposetup() for $TESTTMP/reposetup-test/pull-src4 (glob)

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 (glob)
  reposetup() for $TESTTMP/reposetup-test/parent/sub2 (glob)
  C .hgsub
  C .hgsubstate
  C sub1/1
  C sub2/.hgsub
  C sub2/.hgsubstate
  C sub2/sub21/21
  C sub3/3

  $ cd ..