learning and tests

[S-ign]

Tips:

• please read the style guide before submitting your patch:
  docs/style-guide.md

• commit message titles must be in the form:

topic: Capitalized message with no trailing period

or:

topic, topic2: Capitalized message with no trailing period

• golang code must be formatted according to the standard, please run:

make gofmt		# formats the entire project correctly

or format a single golang file correctly:

gofmt -w yourcode.go

• please rebase your patch against current git master:

git checkout master
git pull origin master
git checkout your-feature
git rebase master
git push your-remote your-feature
hub pull-request	# or submit with the github web ui

• after a patch review, please ping @purpleidea so we know to re-review:

# make changes based on reviews...
git add -p		# add new changes
git commit --amend	# combine with existing commit
git push your-remote your-feature -f
# now ping @purpleidea in the github PR since it doesn't notify us automatically

Thanks for contributing to mgmt and welcome to the team!

[frebib]

We should validate the IP address too: https://golang.org/pkg/net/#ParseIP

[S-ign]

Oh ok, cool, didn't realize there was already an IP Parser, I'll add that! :)

[frebib]

nit: the wording here is slightly confusing given the logic. I would expect either between -0-65536 (exclusive) or preferably between 1-65535 (inclusive). The current wording is exclusive-inclusive which is probably not what the user would expect.

Side note, in many cases a port number of 0 can be valid as it's used to denote "any port". Perhaps we should allow that

[S-ign]

Thanks, I updated this, hopefully, the wording is a little better.

[frebib]

Can we get some IPv6 tests too?
Also some tests for invalid IP address/port combos if you add IP address parsing

[S-ign]

net/ParseIP made this really easy to implement, thanks!

[purpleidea]

Side note, re discussion in IRC:

I noticed that one of the tests failed in an unusual place in this PR... And I said, gah, I hope it's not a race. So I dug into it, and it turns out it was caused by a bug in your code! (yay, no our fault!) So the good news is the tests work, the bad news is I think we could have caught this issue in a more obvious place. So I added a new commit that should help new developers out by providing a clearer error message.

887d374

You'll want to rebase your branch against this commit which is now in git master.

Cheers!

[purpleidea]

@S-ign Hey-- I'm not going to do a full review yet-- I'd like you to first make a small examples/lang/whatever.mcl that uses this function, and confirm you got it doing what you expect. This should replace the copied example that you committed in this PR.

When you've succeeded, please update this PR and put a comment here with the command you used to run this example =D

Thanks!

[purpleidea]

(For anyone else reading, @S-ign came to us for a learning experience, so this is not the traditional review process.)