Add package.xml checks

[cottsay]

It might be useful to add basic checks on the package.xml for a package.

Particularly, I've seen a few packages use <license></license> which doesn't cause any errors, but makes RPM generation fail, and is really against the package.xml format rep: http://www.ros.org/reps/rep-0127.html#license-multiple-but-at-least-one

For the packages who did this, they left it blank because the code was in public domain and was not licensed. I recommended using <license>Public Domain</license>, and all so far have adopted it.

There could also be checks for things such as properly formatted E-mail addresses for authors and maintainers, and properly formatted (and non-empy) URLs.

With the v2 package.xml spec rolling out soon, there will likely be more nuances like this that a lint tool should check.

Great work here!

[mikepurvis]

I agree! This is already being tracked here: #5

The checks you're describing sound less like a linter and more like a validator, which I agree is still needed, but I'd prefer to have as part of catkin_lint or some other external tool.

[cottsay]

Ah! I see the other ticket now.

You have a good point in that it is more like validation. I figured that the linter would be a good place, however, just because much of this does not actually break the package.xml specs, but rather just bends them.

Either way, only suggestions. I'll leave it to you to decide what to do with this ticket. If you feel these checks aren't a good fit for your tool, I understand, and you can close it :)

[mikepurvis]

Will leave open for now, since there are some different ideas in here.

The ideal would be if there were schemas available for both package.xml and launchfiles which could just be validated against.