Intermediate

Set up the WordPress test suite for a plugin, write integration tests, and run them in CI.

Check code against WordPress Coding Standards with PHPCS, fix issues automatically and add it to CI.

Run upgrade routines between plugin versions, migrate data in batches, and stay backwards compatible.

Network activation, per-site tables and options, and testing plugins on Multisite.

Hook into WordPress privacy tools so users can export and erase data your plugin stores.

Deliver updates outside WordPress.org, licence checks and GPL obligations.

Prepare the readme, pass review guidelines, use SVN releases and support users.

Keep plugins fast on large sites: query discipline, caching, lazy loading and avoiding autoload bloat.

Ship blocks, block bindings and editor panels from a plugin, and register meta for the editor.

Declare plugin dependencies in the header, check for them at runtime and degrade gracefully.

Structure larger plugins with namespaces, classes, hook registration and clear responsibilities.

Use Composer autoloading and dependencies in plugins, and prefix vendor code to avoid conflicts.

Run custom queries with $wpdb->prepare, table prefixes, and when to avoid raw SQL.

Organise files, prefix everything, guard direct access and keep the main file small.

Store settings with the Options API, cache expensive results with transients, and watch autoloaded data.

Run setup on activation, clean up on deactivation, and remove data on uninstall when users ask for it.

Manage sites, content, plugins and the database from the command line, and write custom commands.

Add admin menus and submenus with the right capabilities, and render admin pages.

Make code translatable with __ and friends, text domains, JavaScript translations and translation files.

Register settings, sections and fields with sanitisation, so options save securely.