Install rules for test nodelet plugin xmls

[stonier]

Since they are always in package.xml, they should always get installed, otherwise
if they happened to be around in an installspace, then any nodelet manager will
start barfing with "Skipping XML Document" errors (even if they are not loading
this particular nodelet).

[dirk-thomas]

I don't think any of these test files should be installed. Maybe there is a different way to avoid the messages you are referring.

[stonier]

Going to get pretty awkward any other way.

• Don't have pluginlib complain when refreshing the declared class list (here)
• Provide an option to turn off complaints when requesting to refresh the declared class list from the nodelet manager

Both of these would just obscure valid problems for real plugin exports.

• The package.xml marks some special conditions to be triggered by the export.

This would just be complicated...

Honestly, all of the above are undesirable. And any way to change test packages to fit into a 'non-installable' concept would require architectural changes (e.g. don't install their package.xml, nor cmake modules for them) for a special case that doesn't urgently need the attention.

The best solution I can think of would be to get it completely out of the way, i.e. have a nodelet_tests repository, that isn't ever intended for debs or manual installation.

[dirk-thomas]

What about:

• remove the export from the package xml file
• modify the test environment to use a subfolder which contain a custom package which has that export but is only visible to the test

[stonier]

That would work, however it would require some time to learn how to manipulate catkin sub-packages like so. Admittedly it wouldn't take that long, but I do not think I can afford to prioritise the commitment for that given the negligible benefits it would return.