Use is_block_theme in WP_Theme

[spacedmonkey]

In line of 366 / 367 of the WP_Theme class, there are manual calls to if files exists. However, in this context we can use the method is_block_theme. This remove repeated code and hit an existing cache.

• Added the is_block_theme check instead of the file_exists check for the WP_Theme

Trac ticket: https://core.trac.wordpress.org/ticket/58405

[mukesh27]

Hi there!

Thanks for PR/Patch both of you.

@nihar007 in your patch do you use different approach then ​PR 4514? Instead of adding duplicate patch try you can check review the PR and share your feedback on it. Thanks!

[spacedmonkey]

One of the two patches looks good. Moving into the 6.3 milestone.

To who is interested, this needs to be tested in classic and block themes, with and without child themes.

[nihar007]

Hi @mukesh27,
Thanks for you response.

I removed $theme_path variable. I think there is no necessity of $theme_path variable.

Hi @mukeshpanchal27 ,
I have addressed the changes as suggested.
Thank you.

[costdev]

This ticket was discussed during the bug scrub. We agreed to add the needs-testing keyword to indicate that the PR needs testing before commit consideration.

Additional props: @mukesh27 @oglekler

[costdev]

@spacedmonkey From your earlier comment:

To who is interested, this needs to be tested in classic and block themes, with and without child themes.

Would you be able to add some testing instructions so that the Test Team can pick this up and cover possible Dashboard-based and code-based testing paths? Thanks!

Hi @spacedmonkey,
I have made the changes you asked for.
Thank you.

@mukeshpanchal27 @costdev Mind taking a look again?

[spacedmonkey]

@costdev To ensure this statement is hit, create a theme with just a style.css file. You should see an error message in the theme screen in admin. I have provided a screenshot.

@costdev If you are happy, I will commit.

[spacedmonkey]

@costdev If you can test, then I will commit.

[costdev]

Test Report

This report validates that the indicated patch addresses the issue.

Patch tested: ​https://patch-diff.githubusercontent.com/raw/WordPress/wordpress-develop/pull/4514.diff

Steps to Test

1. Create a theme with only a valid style.css and no other files.
2. Navigate to Appearance > Themes.
3. Apply the patch.
4. Refresh the page.

Environment

• WordPress: 6.3-alpha-55505
• PHP: 7.4.33
• Server: Apache/2.4.56 (Ubuntu)
• Database: mysqli (Server: 5.7.41-0ubuntu0.18.04.1 / Client: mysqlnd 7.4.33)
• Browser: Chrome 114.0.0.0 (Windows 10/11)
• Theme: Twenty Twenty-Three 1.1
• MU-Plugins: None activated
• Plugins: None activated

Expected Results

• ✅ The following message should appear before and after the patch:

Actual Results

• ✅ The same message appeared before and after the patch.

@spacedmonkey LGTM and tests well 👍

FYI, this patch brings an additional change (for the better, IMO):
trunk uses file_exists() rather than is_file(), so it's actually possible to create templates/index.html as a directory, and the "Broken Themes" message won't appear on the Appearances > Themes screen. With this PR, the "Broken Themes" message appears as expected.

[spacedmonkey]

In 55885:

Themes: Replace file_exists checks with call to is_block_theme method in WP_Theme class.

In WP_Theme class, replace two calls to file_exists with a call to the method is_block_theme. This method is_block_theme does the same file exists check, but it then caches the result for improved performance.

Props nihar007, spacedmonkey, mukesh27, costdev, juzar.
Fixes #58405.

Committed https://core.trac.wordpress.org/changeset/55885