Create Image_Functions_Usage_Check

[mehulkaklotar]

Description

Checks and warns against the usage of image HTML in templates. Developers are encouraged to use image functions such as wp_get_attachment_image that generate image HTML in templates. The HTML output by these functions is often better as it generates the tag with more performant attributes such as srcset and sizes. No existing sniff exists but the existing WordPress.WP.EnqueuedResources sniff in the WordPress Coding Standards can be used as a starting point.

Acceptance Criteria

• Class Image_Functions_Usage_Check should be created and exists at includes/Checker/Checks
• Class Image_Functions_Usage_Check should extend the PHPCodesniffer_Check abstract class which extends Check interface
• Property $violation code should be warning
• Method run should be implemented from the PHPCodesniffer_Check abstract class if needed
• Check_Result $check_result should be used from the run method parameter to append the results
• $_SERVER['argv'] arguments should be passed to parent run method to provide PHPCS information about standard, report and sniff
• Custom sniff to detect the non-usage of wp image functions

Tests Coverage

• Image_Functions_Usage_Check class expected to extend PHPCodesniffer_Check abstract class
• Image_Functions_Usage_Check class expected to be instance of the PHPCodesniffer_Check class
• run method expected to append results of check into $check_result

[swissspidy]

This should be trivial to implement by following the EnqueuedResourcesSniff implementation, but we need a good regex and a good documentation. Is wp_get_attachment_image the only function to recommend here?

[swissspidy]

From #443:

Image_Functions_Usage_Check: Would warn about any direct output of img tags in PHP code and templates, as those should use wp_get_attachment_image() etc. instead, which comes with performance benefits. The exception is img tags which aren't for attachments. For such manual img tags, the check could trigger a warning if the wp_get_loading_optimization_attributes() is not used as part of generating the output.

For the last part about wp_get_loading_optimization_attributes() I am not sure how feasible that actually is. Maybe just something for the documentation for now.