User Queries: update parameters to take into account changes in WP 5.9

[jeherve]

Fixes #22558

Changes proposed in this Pull Request:

In this core ticket, WP_User_Query was updated to accept a new parameter, capability, to look for specific users.
In turn, the who parameter (in use in Jetpack) was deprecated.

Let's support both parameters for now, with a note to get rid of the backwards compatible code once WordPress 5.9 is required to use Jetpack.

After auditing the codebase, those changes apply to 3 different areas of Jetpack:

• Widget Visibility, as reported in Widget Visibility: WP_User_Query deprecation notice #22558
• Authors Widget
• WPCOM API

Jetpack product discussion

• Primary issue: WordPress 5.9 compatibility #21322

Does this pull request change what data or activity we track or use?

• No

Testing instructions:

• Start with a site with a non-block theme, e.g. the Twenty Twenty theme.
• Add multiple users to your site, with different roles, and publish posts with each user. A quick way to go about it could be to use a plugin like FakerPress to create multiple users and multiple posts at once.
• Edit the name of the users that were created for you, under the Users menu in wp-admin. I would recommend giving subscriber roles a name you remember, for example, "sub", this way you can spot them easily later in the user lists.

Widget Visibility

1. Go to Jetpack > Settings and ensure that the Widget Visibility feature is active.
2. Go to Appearance > Widgets, add a paragraph block.
3. In the block's right sidebar, open the Advanced panel.
4. Add a visibility rule targetting authors
5. Make sure only authors are listed there; subscribers and contributors should not be listed.

Authors Widget

1. Go to Jetpack > Settings and ensure that the Extra sidebar widgets module is active
2. Go to Appearance > Widgets and add an Authors widget to the site.
3. Ensure the options work well.

WPCOM API

1. Go to https://developer.wordpress.com/docs/api/console/
2. In the search field search for "users". You should then be able to build a query for your test site. In the query parameters, ensure the Authors only option is set.

3. Ensure the results are correct.

Once you've done all that, you should not see any PHP notices when checking the site's error log.

[matticbot]

Caution: This PR has changes that must be merged to WordPress.com
Hello jeherve! These changes need to be synced to WordPress.com - If you 're an a11n, please commandeer and confirm D74041-code works as expected before merging this PR. Once this PR is merged, please commit the changes to WP.com. Thank you!
This revision will be updated with each commit to this PR

[github-actions]

Thank you for your PR!

When contributing to Jetpack, we have a few suggestions that can help us test and review your patch:

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Jetpack plugin:

• Next scheduled release: March 1, 2022.
• Scheduled code freeze: February 22, 2022.

[samiff]

All three scenarios tested well for me, great testing instructions 👍

@jeherve Is there a specific way you manage/remember the "todo" tasks like this?

[jeherve]

Is there a specific way you manage/remember the "todo" tasks like this?

I don't know that I have great tips about this. When the time comes to look at updating WordPress requirements for Jetpack, I look for all instances of "WordPress x.x", "x.x", in the codebase, see what comes up. So I guess the most important to me is to add an inline comment mentioning the WordPress version, so it's easier to find afterwards.

[github-actions]

Great news! One last step: head over to your WordPress.com diff, D74041-code, and commit it.
Once you've done so, come back to this PR and add a comment with your changeset ID.

Thank you!

[jeherve]

r239482-wpcom