wc-composable-product/tests/stubs/class-wc-data.php

<?php
/**
 * Minimal WC_Data stub for unit testing.
 */
class WC_Data {
    protected $id = 0;
    protected $data = [];
    protected $meta_data = [];

    public function __construct($id = 0) {
        if (is_numeric($id) && $id > 0) {
            $this->id = (int) $id;
        }
    }

    public function get_id() {
        return $this->id;
    }

    public function set_id($id) {
        $this->id = (int) $id;
    }

    public function get_meta($key, $single = true, $context = 'view') {
        return $this->meta_data[$key] ?? ($single ? '' : []);
    }

    public function update_meta_data($key, $value, $meta_id = 0) {
        $this->meta_data[$key] = $value;
    }

    public function save() {
        return $this->get_id();
    }
}