Administration: Show excerpts for untitled On This Day posts

[alshakero]

Summary

Trac: https://core.trac.wordpress.org/ticket/65658
See: https://wordpress.org/support/topic/on-this-day-widget/

This adds the same untitled-post fallback used in the posts list table to the On This Day dashboard widget. When a matching post has no title, the widget now appends a trimmed excerpt after (no title) when the current user can read the post and the post is not password protected.

The change keeps protected post excerpts hidden and adds PHPUnit coverage for the trimmed excerpt and password-protected cases.

Testing

• Checkout this PR locally and run npm run env:start, then npm run env:install.
• Go to Dashboard (admin:password), you should see the widget.
• Insepect its empty state.
• Import this file to create backdated posts: filexml
• Use the widget.
• Update the post to get rid of the title.
• It should render (no title) 15 word excerpt.

Screenshots

Before

After

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Props alshakero, mukesh27, bph.

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[bph]

Thank you @alshakero for jumping right on it!

[mukeshpanchal27]

Core introduced get_no_title_excerpt() for the upcoming WordPress 7.1 release. See:

wordpress-develop/src/wp-admin/includes/class-wp-posts-list-table.php

Line 1028 in 81b2b5b

protected function get_no_title_excerpt( $post ) {

It looks like this duplicates the functionality we're adding here.

[alshakero]

Yes I actually copied that, but it's protected inside a class. Do you think we should make a util and use it in both places?

[alshakero]

So I checked once more and I think these two functions are only slightly similar to each other.

• WP_Posts_List_Table::get_no_title_excerpt() is list-table-specific, it checks compact mode, current_user_can, and returns already-escaped text.
• The On This Day widget does not need compact mode nor the current_user_can check and it escapes at render time.