Patchwork [2,of,2] help: suggest keyword search when no topic is found

# HG changeset patch
# User Pierre-Yves David <pierre-yves.david@fb.com>
# Date 1397692540 14400
#      Wed Apr 16 19:55:40 2014 -0400
# Node ID 8da30f1d94ece24d09e1bd37048e6c8fdca48b7e
# Parent  a710227126175922ece1d5604edfdf948f348290
help: suggest keyword search when no topic is found

When `hg help foobar` fails, it now suggests using `hg help --keyword foobar`
instead of printing a full page of basic commands.

This should greatly increases discoverability of the `hg help --keyword`
argument.

On Wed, May 07, 2014 at 06:34:03PM -0700, pierre-yves.david@ens-lyon.org wrote:
> # HG changeset patch
> # User Pierre-Yves David <pierre-yves.david@fb.com>
> # Date 1397692540 14400
> #      Wed Apr 16 19:55:40 2014 -0400
> # Node ID 8da30f1d94ece24d09e1bd37048e6c8fdca48b7e
> # Parent  a710227126175922ece1d5604edfdf948f348290
> help: suggest keyword search when no topic is found

These look reasonable. Queued.

>
> When `hg help foobar` fails, it now suggests using `hg help --keyword foobar`
> instead of printing a full page of basic commands.
>
> This should greatly increases discoverability of the `hg help --keyword`
> argument.
>
> diff --git a/mercurial/help.py b/mercurial/help.py
> --- a/mercurial/help.py
> +++ b/mercurial/help.py
> @@ -484,11 +484,10 @@ def help_(ui, name, unknowncmd=False, fu
>          if not rst:
>              msg = _('no matches')
>              hint = _('try "hg help" for a list of topics')
>              raise util.Abort(msg, hint=hint)
>      elif name and name != 'shortlist':
> -        i = None
>          if unknowncmd:
>              queries = (helpextcmd,)
>          elif opts.get('extension'):
>              queries = (helpext,)
>          elif opts.get('command'):
> @@ -496,16 +495,20 @@ def help_(ui, name, unknowncmd=False, fu
>          else:
>              queries = (helptopic, helpcmd, helpext, helpextcmd)
>          for f in queries:
>              try:
>                  rst = f(name)
> -                i = None
>                  break
> -            except error.UnknownCommand, inst:
> -                i = inst
> -        if i:
> -            raise i
> +            except error.UnknownCommand:
> +                pass
> +        else:
> +            if unknowncmd:
> +                raise error.UnknownCommand(name)
> +            else:
> +                msg = _('no such help topic: %s') % name
> +                hint = _('try "hg help --keyword %s"') % name
> +                raise util.Abort(msg, hint=hint)
>      else:
>          # program name
>          if not ui.quiet:
>              rst = [_("Mercurial Distributed SCM\n"), '\n']
>          rst.extend(helplist())
> diff --git a/tests/test-extension.t b/tests/test-extension.t
> --- a/tests/test-extension.t
> +++ b/tests/test-extension.t
> @@ -619,12 +619,12 @@ Broken disabled extension and command:
>    $ 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)
> +  abort: no such help topic: foo
> +  (try "hg help --keyword foo")
>    [255]
>
>    $ cat > throw.py <<EOF
>    > from mercurial import cmdutil, commands
>    > cmdtable = {}
> diff --git a/tests/test-help.t b/tests/test-help.t
> --- a/tests/test-help.t
> +++ b/tests/test-help.t
> @@ -594,34 +594,12 @@ Test command without options
>    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
> +  abort: no such help topic: foo
> +  (try "hg help --keyword foo")
>    [255]
>
>    $ hg skjdfks
>    hg: unknown command 'skjdfks'
>    Mercurial Distributed SCM
> @@ -986,10 +964,17 @@ Test keyword search help
>
>    Extension Commands:
>
>     qclone clone main and patch repository at same time
>
> +Test unfound topic
> +
> +  $ hg help nonexistingtopicthatwillneverexisteverever
> +  abort: no such help topic: nonexistingtopicthatwillneverexisteverever
> +  (try "hg help --keyword nonexistingtopicthatwillneverexisteverever")
> +  [255]
> +
>  Test unfound keyword
>
>    $ hg help --keyword nonexistingwordthatwillneverexisteverever
>    abort: no matches
>    (try "hg help" for a list of topics)
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