SchemaInspector.php

<?php

namespace Drupal\TestTools\Extension;

use Drupal\Core\Extension\ModuleHandlerInterface;

/**
 * Provides methods to access modules' schema.
 */
class SchemaInspector {
    
    /**
     * Returns the module's schema specification.
     *
     * This function can be used to retrieve a schema specification provided by
     * hook_schema(), so it allows you to derive your tables from existing
     * specifications.
     *
     * @param \Drupal\Core\Extension\ModuleHandlerInterface $handler
     *   The module handler to use for calling schema hook.
     * @param string $module
     *   The module to which the table belongs.
     *
     * @return array
     *   An array of schema definition provided by hook_schema().
     *
     * @see \hook_schema()
     */
    public static function getTablesSpecification(ModuleHandlerInterface $handler, string $module) : array {
        if ($handler->loadInclude($module, 'install')) {
            return $handler->invoke($module, 'schema') ?? [];
        }
        return [];
    }

}