Introduce helper function to validate UUID V4

[jonathanbardo]

WordPress 4.7.0 introduced a new helper function that would help with the creation of UUID V4 for customizer transactions but never exposed a way to quickly validate UUID V4 without manually copying over the regex found in class-wp-customize-manager.php. I propose we should introduce an helper function to validate UUID so plugins can quickly generate and validate UUID v4.

[westonruter]

Yeah, I opted to not introduce a new global function because WP has enough globals. But I was probably being overly conservative.

Needs unit tests, good to test with wp_generate_uuid4, that the function returns a valid UUID4.

The Tests_Functions::test_wp_generate_uuid4() test then also should be refactored similarly.

[jonathanbardo]

It's true that WordPress does have a lot of global functions! I just recently started using that function in a plugin and was going to duplicate the regex myself and I thought that it would have been useful to have a validating function in core since we have a generating function.

Something I noticed while writing the unit test is that the regex used in class-wp-customize-manager.php wasn't the same as in the functions.php unit test and was way more permissive. Any reason for that @westonruter ? I think the regex that was in the unit test is the right one for UUID v4.

[westonruter]

I'm trying to recall. Either the the manager was just a generic UUID regex I found, or it was also intended to allow for a system to generate a UUID without it necessarily having to be a UUID4.

[jonathanbardo]

@westonruter Latest patch will only enforce validating a UUID V4 if the version parameter is provided and set to 4 and will be checking if we are dealing with a general UUID string otherwise.

[jbpaul17]

This needs a review and an owner if its going to land in 4.8.

[westonruter]

Refreshed patch

[westonruter]

​https://github.com/xwp/wordpress-develop/pull/259

[westonruter]

In 39778.4.diff​ I decided to rename it to just wp_is_uuid().

Other minor changes to generic.39778.2.diff​ can be seen here: ​https://github.com/xwp/wordpress-develop/pull/259/files/8918834..3356962

[westonruter]

In 41388:

Customize: Add wp_is_uuid() validation function with optional second $version=4 parameter to enforce v4 random UUIDs.

Props jonathanbardo.
Fixes #39778.