Sorry I've combined two issues here, should've filed two bugs.

To clarify, my patch does not fix this issue, it just improves the spec file.

Created attachment 1108677 [details]
0001-validate-appdata.xml-file.patch

So this looks like the key bit:

> (org.gnome.Software:16784): Gs-DEBUG: removing incompatible
> www.octave.org-octave.desktop from project group GNU

If I remove this line from www.octave.org-octave.appdata.xml

   <project_group>GNU</project_group>

then "killall gnome-software; gnome-software --verbose" correctly shows Octave.

I'm curious about this.  Re-assigning to gnome-software to bring in those folks.  While http://people.freedesktop.org/~hughsient/appdata/ doesn't seem to be completely explicit that <project_group> should/must be a desktop environment, gnome-software appears to assume that it is and uses it to exclude "incompatible" software.  Richard - what's the intent here?

I'm not Richard and don't really know the whole story here, but looking at the code the list of allowed values for <project_group> is taken from https://github.com/hughsie/appstream-glib/blob/master/libappstream-glib/as-environment-ids.txt

Thanks!  I filed https://github.com/hughsie/appstream-glib/issues/73 for appstream-util to validate against that list.

Send fix to upstream Octave: https://savannah.gnu.org/patch/?8842.

@Orion, we could probably do this in the octave.spec to fix this...

octave-4.0.0-8.fc23 has been submitted as an update to Fedora 23. https://bodhi.fedoraproject.org/updates/FEDORA-2015-8f6ad2a67a

octave-4.0.0-8.fc23 has been pushed to the Fedora 23 testing repository. If problems still persist, please make note of it in this bug report.
See https://fedoraproject.org/wiki/QA:Updates_Testing for
instructions on how to install test updates.
You can provide feedback for this update here: https://bodhi.fedoraproject.org/updates/FEDORA-2015-8f6ad2a67a

octave-4.0.0-8.fc23 has been pushed to the Fedora 23 stable repository. If problems still persist, please make note of it in this bug report.

Richard - can you comment on this?  From the description of <project_group>, the octave folk feel that GNU would be an appropriate description for octave.  If this tag is to be limited to a specific set of desktop environments, this needs to be made more specific.

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I looked at why octave isn't still showing up in the appstream metadata and apparently it's now erroring out because the <license> isn't a valid SPDX license:

AppData ./tmp/fedora-26/octave-4.2.0-11.fc26/usr/share/appdata/www.octave.org-octave.appdata.xml license 'GPLv3+' invalid

https://github.com/hughsie/createrepo_as_logs/blob/master/o/octave.log

I've pushed a quick fix to rawhide, let's see if that makes it work tomorrow. I would appreciate if someone who knows how upstream patch submission works could forward this upstream. Thanks!

http://pkgs.fedoraproject.org/cgit/rpms/octave.git/commit/?id=d752630df28336be61ccd8e7ac3cd33cd2fb09d1

Filed upstream: https://savannah.gnu.org/bugs/index.php?49952

This bug appears to have been reported against 'rawhide' during the Fedora 26 development cycle.
Changing version to '26'.

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I think this has all been dealt with upstream.