help: add topic rewriting hooks

They are useful when updating help topics dynamically from extensions.

mercurial/help.py

@@ -1,104 +1,116 b''
 # help.py - help data for mercurial
 #
 # Copyright 2006 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.
 
 from i18n import gettext, _
 import sys, os
 import extensions
 
 
 def moduledoc(file):
     '''return the top-level python documentation for the given file
 
     Loosely inspired by pydoc.source_synopsis(), but rewritten to
     handle triple quotes and to return the whole text instead of just
     the synopsis'''
     result = []
 
     line = file.readline()
     while line[:1] == '#' or not line.strip():
         line = file.readline()
         if not line:
             break
 
     start = line[:3]
     if start == '"""' or start == "'''":
         line = line[3:]
         while line:
             if line.rstrip().endswith(start):
                 line = line.split(start)[0]
                 if line:
                     result.append(line)
                 break
             elif not line:
                 return None # unmatched delimiter
             result.append(line)
             line = file.readline()
     else:
         return None
 
     return ''.join(result)
 
 def listexts(header, exts, maxlength, indent=1):
     '''return a text listing of the given extensions'''
     if not exts:
         return ''
     result = '\n%s\n\n' % header
     for name, desc in sorted(exts.iteritems()):
         result += '%s%-*s %s\n' % (' ' * indent, maxlength + 2,
                                    ':%s:' % name, desc)
     return result
 
 def extshelp():
     doc = loaddoc('extensions')()
 
     exts, maxlength = extensions.enabled()
     doc += listexts(_('enabled extensions:'), exts, maxlength)
 
     exts, maxlength = extensions.disabled()
     doc += listexts(_('disabled extensions:'), exts, maxlength)
 
     return doc
 
 def loaddoc(topic):
     """Return a delayed loader for help/topic.txt."""
 
     def loader():
         if hasattr(sys, 'frozen'):
             module = sys.executable
         else:
             module = __file__
         base = os.path.dirname(module)
 
         for dir in ('.', '..'):
             docdir = os.path.join(base, dir, 'help')
             if os.path.isdir(docdir):
                 break
 
         path = os.path.join(docdir, topic + ".txt")
-        return gettext(open(path).read())
+        doc = gettext(open(path).read())
+        for rewriter in helphooks.get(topic, []):
+            doc = rewriter(topic, doc)
+        return doc
+
     return loader
 
 helptable = [
     (["config", "hgrc"], _("Configuration Files"), loaddoc('config')),
     (["dates"], _("Date Formats"), loaddoc('dates')),
     (["patterns"], _("File Name Patterns"), loaddoc('patterns')),
     (['environment', 'env'], _('Environment Variables'),
      loaddoc('environment')),
     (['revs', 'revisions'], _('Specifying Single Revisions'),
      loaddoc('revisions')),
     (['mrevs', 'multirevs'], _('Specifying Multiple Revisions'),
      loaddoc('multirevs')),
     (['revset', 'revsets'], _("Specifying Revision Sets"), loaddoc('revsets')),
     (['diffs'], _('Diff Formats'), loaddoc('diffs')),
     (['merge-tools'], _('Merge Tools'), loaddoc('merge-tools')),
     (['templating', 'templates'], _('Template Usage'),
      loaddoc('templates')),
     (['urls'], _('URL Paths'), loaddoc('urls')),
     (["extensions"], _("Using additional features"), extshelp),
     (["hgweb"], _("Configuring hgweb"), loaddoc('hgweb')),
     (["glossary"], _("Glossary"), loaddoc('glossary')),
 ]
+
+# Map topics to lists of callable taking the current topic help and
+# returning the updated version
+helphooks = {
+}
+
+def addtopichook(topic, rewriter):
+    helphooks.setdefault(topic, []).append(rewriter)

tests/test-help.t

@@ -1,758 +1,785 b''
 Short help:
 
   $ hg
   Mercurial Distributed SCM
   
   basic commands:
   
    add        add the specified files on the next commit
    annotate   show changeset information by line for each file
    clone      make a copy of an existing repository
    commit     commit the specified files or all outstanding changes
    diff       diff repository (or selected files)
    export     dump the header and diffs for one or more changesets
    forget     forget the specified files on the next commit
    init       create a new repository in the given directory
    log        show revision history of entire repository or files
    merge      merge working directory with another revision
    pull       pull changes from the specified source
    push       push changes to the specified destination
    remove     remove the specified files on the next commit
    serve      start stand-alone webserver
    status     show changed files in the working directory
    summary    summarize working directory state
    update     update working directory (or switch revisions)
   
   use "hg help" for the full list of commands or "hg -v" for details
 
   $ hg -q
    add        add the specified files on the next commit
    annotate   show changeset information by line for each file
    clone      make a copy of an existing repository
    commit     commit the specified files or all outstanding changes
    diff       diff repository (or selected files)
    export     dump the header and diffs for one or more changesets
    forget     forget the specified files on the next commit
    init       create a new repository in the given directory
    log        show revision history of entire repository or files
    merge      merge working directory with another revision
    pull       pull changes from the specified source
    push       push changes to the specified destination
    remove     remove the specified files on the next commit
    serve      start stand-alone webserver
    status     show changed files in the working directory
    summary    summarize working directory state
    update     update working directory (or switch revisions)
 
   $ hg help
   Mercurial Distributed SCM
   
   list of commands:
   
    add          add the specified files on the next commit
    addremove    add all new files, delete all missing files
    annotate     show changeset information by line for each file
    archive      create an unversioned archive of a repository revision
    backout      reverse effect of earlier changeset
    bisect       subdivision search of changesets
    branch       set or show the current branch name
    branches     list repository named branches
    bundle       create a changegroup file
    cat          output the current or given revision of files
    clone        make a copy of an existing repository
    commit       commit the specified files or all outstanding changes
    copy         mark files as copied for the next commit
    diff         diff repository (or selected files)
    export       dump the header and diffs for one or more changesets
    forget       forget the specified files on the next commit
    grep         search for a pattern in specified files and revisions
    heads        show current repository heads or show branch heads
    help         show help for a given topic or a help overview
    identify     identify the working copy or specified revision
    import       import an ordered set of patches
    incoming     show new changesets found in source
    init         create a new repository in the given directory
    locate       locate files matching specific patterns
    log          show revision history of entire repository or files
    manifest     output the current or given revision of the project manifest
    merge        merge working directory with another revision
    outgoing     show changesets not found in the destination
    parents      show the parents of the working directory or revision
    paths        show aliases for remote repositories
    pull         pull changes from the specified source
    push         push changes to the specified destination
    recover      roll back an interrupted transaction
    remove       remove the specified files on the next commit
    rename       rename files; equivalent of copy + remove
    resolve      redo merges or set/view the merge status of files
    revert       restore individual files or directories to an earlier state
    rollback     roll back the last transaction (dangerous)
    root         print the root (top) of the current working directory
    serve        start stand-alone webserver
    showconfig   show combined config settings from all hgrc files
    status       show changed files in the working directory
    summary      summarize working directory state
    tag          add one or more tags for the current or given revision
    tags         list repository tags
    tip          show the tip revision
    unbundle     apply one or more changegroup files
    update       update working directory (or switch revisions)
    verify       verify the integrity of the repository
    version      output version and copyright information
   
   additional help topics:
   
    config       Configuration Files
    dates        Date Formats
    patterns     File Name Patterns
    environment  Environment Variables
    revisions    Specifying Single Revisions
    multirevs    Specifying Multiple Revisions
    revsets      Specifying Revision Sets
    diffs        Diff Formats
    merge-tools  Merge Tools
    templating   Template Usage
    urls         URL Paths
    extensions   Using additional features
    hgweb        Configuring hgweb
    glossary     Glossary
   
   use "hg -v help" to show aliases and global options
 
   $ hg -q help
    add          add the specified files on the next commit
    addremove    add all new files, delete all missing files
    annotate     show changeset information by line for each file
    archive      create an unversioned archive of a repository revision
    backout      reverse effect of earlier changeset
    bisect       subdivision search of changesets
    branch       set or show the current branch name
    branches     list repository named branches
    bundle       create a changegroup file
    cat          output the current or given revision of files
    clone        make a copy of an existing repository
    commit       commit the specified files or all outstanding changes
    copy         mark files as copied for the next commit
    diff         diff repository (or selected files)
    export       dump the header and diffs for one or more changesets
    forget       forget the specified files on the next commit
    grep         search for a pattern in specified files and revisions
    heads        show current repository heads or show branch heads
    help         show help for a given topic or a help overview
    identify     identify the working copy or specified revision
    import       import an ordered set of patches
    incoming     show new changesets found in source
    init         create a new repository in the given directory
    locate       locate files matching specific patterns
    log          show revision history of entire repository or files
    manifest     output the current or given revision of the project manifest
    merge        merge working directory with another revision
    outgoing     show changesets not found in the destination
    parents      show the parents of the working directory or revision
    paths        show aliases for remote repositories
    pull         pull changes from the specified source
    push         push changes to the specified destination
    recover      roll back an interrupted transaction
    remove       remove the specified files on the next commit
    rename       rename files; equivalent of copy + remove
    resolve      redo merges or set/view the merge status of files
    revert       restore individual files or directories to an earlier state
    rollback     roll back the last transaction (dangerous)
    root         print the root (top) of the current working directory
    serve        start stand-alone webserver
    showconfig   show combined config settings from all hgrc files
    status       show changed files in the working directory
    summary      summarize working directory state
    tag          add one or more tags for the current or given revision
    tags         list repository tags
    tip          show the tip revision
    unbundle     apply one or more changegroup files
    update       update working directory (or switch revisions)
    verify       verify the integrity of the repository
    version      output version and copyright information
   
   additional help topics:
   
    config       Configuration Files
    dates        Date Formats
    patterns     File Name Patterns
    environment  Environment Variables
    revisions    Specifying Single Revisions
    multirevs    Specifying Multiple Revisions
    revsets      Specifying Revision Sets
    diffs        Diff Formats
    merge-tools  Merge Tools
    templating   Template Usage
    urls         URL Paths
    extensions   Using additional features
    hgweb        Configuring hgweb
    glossary     Glossary
 
 Test short command list with verbose option
 
   $ hg -v help shortlist
   Mercurial Distributed SCM (version *) (glob)
   
   Copyright (C) 2005-2010 Matt Mackall <[e-mail]> and others
   This is free software; see the source for copying conditions. There is NO
   warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   
   basic commands:
   
    add:
         add the specified files on the next commit
    annotate, blame:
         show changeset information by line for each file
    clone:
         make a copy of an existing repository
    commit, ci:
         commit the specified files or all outstanding changes
    diff:
         diff repository (or selected files)
    export:
         dump the header and diffs for one or more changesets
    forget:
         forget the specified files on the next commit
    init:
         create a new repository in the given directory
    log, history:
         show revision history of entire repository or files
    merge:
         merge working directory with another revision
    pull:
         pull changes from the specified source
    push:
         push changes to the specified destination
    remove, rm:
         remove the specified files on the next commit
    serve:
         start stand-alone webserver
    status, st:
         show changed files in the working directory
    summary, sum:
         summarize working directory state
    update, up, checkout, co:
         update working directory (or switch revisions)
   
   global options:
    -R --repository REPO    repository root directory or name of overlay bundle
                            file
       --cwd DIR            change working directory
    -y --noninteractive     do not prompt, assume 'yes' for any required answers
    -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
   
   [+] marked option can be specified multiple times
   
   use "hg help" for the full list of commands
 
   $ hg add -h
   hg add [OPTION]... [FILE]...
   
   add the specified files on the next commit
   
       Schedule files to be version controlled and added to the repository.
   
       The files will be added to the repository at the next commit. To undo an
       add before that, see "hg forget".
   
       If no names are given, add all files to the repository.
   
       Returns 0 if all files are successfully added.
   
   use "hg -v help add" to show verbose help
   
   options:
   
    -I --include PATTERN [+]  include names matching the given patterns
    -X --exclude PATTERN [+]  exclude names matching the given patterns
    -S --subrepos             recurse into subrepositories
    -n --dry-run              do not perform actions, just print output
   
   [+] marked option can be specified multiple times
   
   use "hg -v help add" to show global options
 
 Verbose help for add
 
   $ hg add -hv
   hg add [OPTION]... [FILE]...
   
   add the specified files on the next commit
   
       Schedule files to be version controlled and added to the repository.
   
       The files will be added to the repository at the next commit. To undo an
       add before that, see "hg forget".
   
       If no names are given, add all files to the repository.
   
       An example showing how new (unknown) files are added automatically by "hg
       add":
   
         $ ls
         foo.c
         $ hg status
         ? foo.c
         $ hg add
         adding foo.c
         $ hg status
         A foo.c
   
       Returns 0 if all files are successfully added.
   
   options:
   
    -I --include PATTERN [+]  include names matching the given patterns
    -X --exclude PATTERN [+]  exclude names matching the given patterns
    -S --subrepos             recurse into subrepositories
    -n --dry-run              do not perform actions, just print output
   
   global options:
    -R --repository REPO      repository root directory or name of overlay bundle
                              file
       --cwd DIR              change working directory
    -y --noninteractive       do not prompt, assume 'yes' for any required
                              answers
    -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
   
   [+] marked option can be specified multiple times
 
 Test help option with version option
 
   $ hg add -h --version
   Mercurial Distributed SCM (version *) (glob)
   
   Copyright (C) 2005-2010 Matt Mackall <[e-mail]> and others
   This is free software; see the source for copying conditions. There is NO
   warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
   
   hg add [OPTION]... [FILE]...
   
   add the specified files on the next commit
   
       Schedule files to be version controlled and added to the repository.
   
       The files will be added to the repository at the next commit. To undo an
       add before that, see "hg forget".
   
       If no names are given, add all files to the repository.
   
       Returns 0 if all files are successfully added.
   
   use "hg -v help add" to show verbose help
   
   options:
   
    -I --include PATTERN [+]  include names matching the given patterns
    -X --exclude PATTERN [+]  exclude names matching the given patterns
    -S --subrepos             recurse into subrepositories
    -n --dry-run              do not perform actions, just print output
   
   [+] marked option can be specified multiple times
   
   use "hg -v help add" to show global options
 
   $ hg add --skjdfks
   hg add: option --skjdfks not recognized
   hg add [OPTION]... [FILE]...
   
   add the specified files on the next commit
   
       Schedule files to be version controlled and added to the repository.
   
       The files will be added to the repository at the next commit. To undo an
       add before that, see "hg forget".
   
       If no names are given, add all files to the repository.
   
       Returns 0 if all files are successfully added.
   
   use "hg -v help add" to show verbose help
   
   options:
   
    -I --include PATTERN [+]  include names matching the given patterns
    -X --exclude PATTERN [+]  exclude names matching the given patterns
    -S --subrepos             recurse into subrepositories
    -n --dry-run              do not perform actions, just print output
   
   [+] marked option can be specified multiple times
   
   use "hg -v help add" to show global options
   [255]
 
 Test ambiguous command help
 
   $ hg help ad
   list of commands:
   
    add         add the specified files on the next commit
    addremove   add all new files, delete all missing files
   
   use "hg -v help ad" to show aliases and global options
 
 Test command without options
 
   $ hg help verify
   hg verify
   
   verify the integrity of the repository
   
       Verify the integrity of the current repository.
   
       This will perform an extensive check of the repository's integrity,
       validating the hashes and checksums of each entry in the changelog,
       manifest, and tracked files, as well as the integrity of their crosslinks
       and indices.
   
       Returns 0 on success, 1 if errors are encountered.
   
   use "hg -v help verify" to show global options
 
   $ hg help diff
   hg diff [OPTION]... ([-c REV] | [-r REV1 [-r REV2]]) [FILE]...
   
   diff repository (or selected files)
   
       Show differences between revisions for the specified files.
   
       Differences between files are shown using the unified diff format.
   
       Note:
          diff may generate unexpected results for merges, as it will default to
          comparing against the working directory's first parent changeset if no
          revisions are specified.
   
       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.
   
       Alternatively you can specify -c/--change with a revision to see the
       changes in that changeset relative to its first parent.
   
       Without the -a/--text option, diff will avoid generating diffs of files it
       detects as binary. With -a, diff will generate a diff anyway, probably
       with undesirable results.
   
       Use the -g/--git option to generate diffs in the git extended diff format.
       For more information, read "hg help diffs".
   
       Returns 0 on success.
   
   options:
   
    -r --rev REV [+]          revision
    -c --change REV           change made by revision
    -a --text                 treat all files as text
    -g --git                  use git extended diff format
       --nodates              omit dates from diff headers
    -p --show-function        show which function each change is in
       --reverse              produce a diff that undoes the changes
    -w --ignore-all-space     ignore white space when comparing lines
    -b --ignore-space-change  ignore changes in the amount of white space
    -B --ignore-blank-lines   ignore changes whose lines are all blank
    -U --unified NUM          number of lines of context to show
       --stat                 output diffstat-style summary of changes
    -I --include PATTERN [+]  include names matching the given patterns
    -X --exclude PATTERN [+]  exclude names matching the given patterns
    -S --subrepos             recurse into subrepositories
   
   [+] marked option can be specified multiple times
   
   use "hg -v help diff" to show global options
 
   $ hg help status
   hg status [OPTION]... [FILE]...
   
   aliases: st
   
   show changed files in the working directory
   
       Show status of files in the repository. If names are given, only files
       that match are shown. Files that are clean or ignored or the source of a
       copy/move operation, are not listed unless -c/--clean, -i/--ignored,
       -C/--copies or -A/--all are given. Unless options described with "show
       only ..." are given, the options -mardu are used.
   
       Option -q/--quiet hides untracked (unknown and ignored) files unless
       explicitly requested with -u/--unknown or -i/--ignored.
   
       Note:
          status may appear to disagree with diff if permissions have changed or
          a merge has occurred. The standard diff format does not report
          permission changes and diff only reports changes relative to one merge
          parent.
   
       If one revision is given, it is used as the base revision. If two
       revisions are given, the differences between them are shown. The --change
       option can also be used as a shortcut to list the changed files of a
       revision from its first parent.
   
       The codes used to show the status of files are:
   
         M = modified
         A = added
         R = removed
         C = clean
         ! = missing (deleted by non-hg command, but still tracked)
         ? = not tracked
         I = ignored
           = origin of the previous file listed as A (added)
   
       Returns 0 on success.
   
   options:
   
    -A --all                  show status of all files
    -m --modified             show only modified files
    -a --added                show only added files
    -r --removed              show only removed files
    -d --deleted              show only deleted (but tracked) files
    -c --clean                show only files without changes
    -u --unknown              show only unknown (not tracked) files
    -i --ignored              show only ignored files
    -n --no-status            hide status prefix
    -C --copies               show source of copied files
    -0 --print0               end filenames with NUL, for use with xargs
       --rev REV [+]          show difference from revision
       --change REV           list the changed files of a revision
    -I --include PATTERN [+]  include names matching the given patterns
    -X --exclude PATTERN [+]  exclude names matching the given patterns
    -S --subrepos             recurse into subrepositories
   
   [+] marked option can be specified multiple times
   
   use "hg -v help status" to show global options
 
   $ hg -q help status
   hg status [OPTION]... [FILE]...
   
   show changed files in the working directory
 
   $ hg help foo
   hg: unknown command 'foo'
   Mercurial Distributed SCM
   
   basic commands:
   
    add        add the specified files on the next commit
    annotate   show changeset information by line for each file
    clone      make a copy of an existing repository
    commit     commit the specified files or all outstanding changes
    diff       diff repository (or selected files)
    export     dump the header and diffs for one or more changesets
    forget     forget the specified files on the next commit
    init       create a new repository in the given directory
    log        show revision history of entire repository or files
    merge      merge working directory with another revision
    pull       pull changes from the specified source
    push       push changes to the specified destination
    remove     remove the specified files on the next commit
    serve      start stand-alone webserver
    status     show changed files in the working directory
    summary    summarize working directory state
    update     update working directory (or switch revisions)
   
   use "hg help" for the full list of commands or "hg -v" for details
   [255]
 
   $ hg skjdfks
   hg: unknown command 'skjdfks'
   Mercurial Distributed SCM
   
   basic commands:
   
    add        add the specified files on the next commit
    annotate   show changeset information by line for each file
    clone      make a copy of an existing repository
    commit     commit the specified files or all outstanding changes
    diff       diff repository (or selected files)
    export     dump the header and diffs for one or more changesets
    forget     forget the specified files on the next commit
    init       create a new repository in the given directory
    log        show revision history of entire repository or files
    merge      merge working directory with another revision
    pull       pull changes from the specified source
    push       push changes to the specified destination
    remove     remove the specified files on the next commit
    serve      start stand-alone webserver
    status     show changed files in the working directory
    summary    summarize working directory state
    update     update working directory (or switch revisions)
   
   use "hg help" for the full list of commands or "hg -v" for details
   [255]
 
   $ cat > helpext.py <<EOF
   > import os
   > from mercurial import commands
   > 
   > def nohelp(ui, *args, **kwargs):
   >     pass
   > 
   > cmdtable = {
   >     "nohelp": (nohelp, [], "hg nohelp"),
   > }
   > 
   > commands.norepo += ' nohelp'
   > EOF
   $ echo '[extensions]' >> $HGRCPATH
   $ echo "helpext = `pwd`/helpext.py" >> $HGRCPATH
 
 Test command with no help text
 
   $ hg help nohelp
   hg nohelp
   
   (no help text available)
   
   use "hg -v help nohelp" to show global options
 
 Test that default list of commands omits extension commands
 
   $ hg help
   Mercurial Distributed SCM
   
   list of commands:
   
    add          add the specified files on the next commit
    addremove    add all new files, delete all missing files
    annotate     show changeset information by line for each file
    archive      create an unversioned archive of a repository revision
    backout      reverse effect of earlier changeset
    bisect       subdivision search of changesets
    branch       set or show the current branch name
    branches     list repository named branches
    bundle       create a changegroup file
    cat          output the current or given revision of files
    clone        make a copy of an existing repository
    commit       commit the specified files or all outstanding changes
    copy         mark files as copied for the next commit
    diff         diff repository (or selected files)
    export       dump the header and diffs for one or more changesets
    forget       forget the specified files on the next commit
    grep         search for a pattern in specified files and revisions
    heads        show current repository heads or show branch heads
    help         show help for a given topic or a help overview
    identify     identify the working copy or specified revision
    import       import an ordered set of patches
    incoming     show new changesets found in source
    init         create a new repository in the given directory
    locate       locate files matching specific patterns
    log          show revision history of entire repository or files
    manifest     output the current or given revision of the project manifest
    merge        merge working directory with another revision
    outgoing     show changesets not found in the destination
    parents      show the parents of the working directory or revision
    paths        show aliases for remote repositories
    pull         pull changes from the specified source
    push         push changes to the specified destination
    recover      roll back an interrupted transaction
    remove       remove the specified files on the next commit
    rename       rename files; equivalent of copy + remove
    resolve      redo merges or set/view the merge status of files
    revert       restore individual files or directories to an earlier state
    rollback     roll back the last transaction (dangerous)
    root         print the root (top) of the current working directory
    serve        start stand-alone webserver
    showconfig   show combined config settings from all hgrc files
    status       show changed files in the working directory
    summary      summarize working directory state
    tag          add one or more tags for the current or given revision
    tags         list repository tags
    tip          show the tip revision
    unbundle     apply one or more changegroup files
    update       update working directory (or switch revisions)
    verify       verify the integrity of the repository
    version      output version and copyright information
   
   enabled extensions:
   
    helpext  (no help text available)
   
   additional help topics:
   
    config       Configuration Files
    dates        Date Formats
    patterns     File Name Patterns
    environment  Environment Variables
    revisions    Specifying Single Revisions
    multirevs    Specifying Multiple Revisions
    revsets      Specifying Revision Sets
    diffs        Diff Formats
    merge-tools  Merge Tools
    templating   Template Usage
    urls         URL Paths
    extensions   Using additional features
    hgweb        Configuring hgweb
    glossary     Glossary
   
   use "hg -v help" to show aliases and global options
 
 Test list of commands with command with no help text
 
   $ hg help helpext
   helpext extension - no help text available
   
   list of commands:
   
    nohelp   (no help text available)
   
   use "hg -v help helpext" to show aliases and global options
 
 Test a help topic
 
   $ hg help revs
   Specifying Single Revisions
   
       Mercurial supports several ways to specify individual revisions.
   
       A plain integer is treated as a revision number. Negative integers are
       treated as sequential offsets from the tip, with -1 denoting the tip, -2
       denoting the revision prior to the tip, and so forth.
   
       A 40-digit hexadecimal string is treated as a unique revision identifier.
   
       A hexadecimal string less than 40 characters long is treated as a unique
       revision identifier and is referred to as a short-form identifier. A
       short-form identifier is only valid if it is the prefix of exactly one
       full-length identifier.
   
       Any other string is treated as a tag or branch name. A tag name is a
       symbolic name associated with a revision identifier. A branch name denotes
       the tipmost revision of that branch. Tag and branch names must not contain
       the ":" character.
   
       The reserved name "tip" is a special tag that always identifies the most
       recent revision.
   
       The reserved name "null" indicates the null revision. This is the revision
       of an empty repository, and the parent of revision 0.
   
       The reserved name "." indicates the working directory parent. If no
       working directory is checked out, it is equivalent to null. If an
       uncommitted merge is in progress, "." is the revision of the first parent.
+
+Test help hooks
+
+  $ cat > helphook1.py <<EOF
+  > from mercurial import help
+  > 
+  > def rewrite(topic, doc):
+  >     return doc + '\nhelphook1\n'
+  > 
+  > def extsetup(ui):
+  >     help.addtopichook('revsets', rewrite)
+  > EOF
+  $ cat > helphook2.py <<EOF
+  > from mercurial import help
+  > 
+  > def rewrite(topic, doc):
+  >     return doc + '\nhelphook2\n'
+  > 
+  > def extsetup(ui):
+  >     help.addtopichook('revsets', rewrite)
+  > EOF
+  $ echo '[extensions]' >> $HGRCPATH
+  $ echo "helphook1 = `pwd`/helphook1.py" >> $HGRCPATH
+  $ echo "helphook2 = `pwd`/helphook2.py" >> $HGRCPATH
+  $ hg help revsets | grep helphook
+      helphook1
+      helphook2