`wp_get_plugin_action_button()` can return `void`.

[costdev]

[57545] introduced wp_get_plugin_action_button(). This function is documented to return a string.

However, the return $button; line is misplaced inside the following conditions:

if ( current_user_can( 'install_plugins' ) || current_user_can( 'update_plugins' ) ) {

As a result, when the user does not have the appropriate capabilities, the return line is not hit, and the function returns void.

[rajinsharwar]

For ease of testing this, I have just inversed the capability check so that I can test the patch with the admin user.

1. Before Patch, the call to wp_get_plugin_action_button() is returning void: ​https://prnt.sc/pOTrSJ8-nVOG ✅
2. After Patch, the call to wp_get_plugin_action_button() is returning an empty string: ​https://prnt.sc/oi7IqWLBNhVq ✅

This is now working to return a string irrespective of the result of the capability check. Marking this for 'commit' as it has both manual and unit tests passed.

[hellofromTonya]

Patch: https://core.trac.wordpress.org/ticket/61400

Reviewed and is ready for commit.

[hellofromTonya]

Setting myself to owner for its review (already done) and commit.

[hellofromTonya]

In 58396:

Plugins: Ensure wp_get_plugin_action_button() returns a string.

[57545] introduced wp_get_plugin_action_button(). This function is documented to return a string. However, if the user does not have the appropriate capabilities, it returned void, which is unexpected.

Resolves the issue by moving the return $button to the bottom of the function to ensure it always returns a string type. On success, the button's HTML string is returned; else, an empty string is returned.

Unit tests are included.

Follow-up to [57545].

Props costdev, rajinsharwar, hellofromTonya.
Fixes #61400.

Committed via https://core.trac.wordpress.org/changeset/58396.

[hellofromTonya]

@jorbin @costdev if there's a 6.5.5, r58396 might be a good candidate to backport.

[jorbin]

[58396] looks good for backport to the 6.5 branch. I don't think this should trigger a 6.5.5, but it would be good to include it if one takes place.

[hellofromTonya]

In 58445:

Plugins: Ensure wp_get_plugin_action_button() returns a string.

[57545] introduced wp_get_plugin_action_button(). This function is documented to return a string. However, if the user does not have the appropriate capabilities, it returned void, which is unexpected.

Resolves the issue by moving the return $button to the bottom of the function to ensure it always returns a string type. On success, the button's HTML string is returned; else, an empty string is returned.

Unit tests are included.

Follow-up to [57545].

Reviewed by jorbin.
Merges [58396] to the 6.5 branch.

Props costdev, rajinsharwar, hellofromTonya.
Fixes #61400.