Roles endpoint: Use instance of for checking wp roles

[darssen]

Fixes a Fatal in wpcom when using the endpoint with the force=wpcom param.

Based on https://bugs.php.net/bug.php?id=79623 it looks like this was introduced when switching to PHP8

Proposed changes:

Use instanceof WP_Roles check instead of method_exists since in the Jetpack Shadow Site $wp_roles is an array not an object.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

b3afe066ca610f6dd94a60779e59882e-logstash

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

No

Testing instructions:

Call the endpoints for 3 scenarios:

Simple site (Should go through WPCOM)

• Test without the patch applied.
• Test with the patch applied using instructions given by bot below.

Jetpack site

• Test without the patch applied.
• Test with the patch applied in your local site.

Jetpack site with query_param force=wpcom (Should go through WPCOM)

• Test without the patch applied. It should fatal
• Test with the patch applied using instructions given by bot below.

[github-actions]

Are you an Automattician? Please test your changes on all WordPress.com environments to help mitigate accidental explosions.

• To test on WoA, go to the Plugins menu on a WordPress.com Simple site. Click on the "Upload" button and follow the upgrade flow to be able to upload, install, and activate the Jetpack Beta plugin. Once the plugin is active, go to Jetpack > Jetpack Beta, select your plugin, and enable the update/use-instance-of-for-checking-wp-roles branch.

• To test on Simple, run the following command on your sandbox:

  bin/jetpack-downloader test jetpack update/use-instance-of-for-checking-wp-roles
  

Interested in more tips and information?

• In your local development environment, use the jetpack rsync command to sync your changes to a WoA dev blog.
• Read more about our development workflow here: PCYsg-eg0-p2
• Figure out when your changes will be shipped to customers here: PCYsg-eg5-p2

[github-actions]

Thank you for your PR!

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Jetpack plugin:

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[fgiannar]

Maybe we could be more defensive here and also check if $wp_roles is actually an array next?

[darssen]

Thanks for reviewing, I addressed it in 6540dbd

[fgiannar]

Works great!

Tested on both Jetpack and Simple sites and ensured we don't fatal anymore for requests for Jetpack sites with ?force=wpcom