add_meta_data( 'test_data', 'test' ); $filter = function ( $exclude_meta, $existing_meta_keys ) { $this->assertContains( 'test_data', $existing_meta_keys ); return array( 'test_data' ); }; add_filter( 'woocommerce_duplicate_product_exclude_meta', $filter, 10, 2 ); $duplicate = ( new WC_Admin_Duplicate_Product() )->product_duplicate( $product ); remove_filter( 'woocommerce_duplicate_product_exclude_meta', $filter ); $this->assertNotEquals( $product->get_id(), $duplicate->get_id() ); $this->assertEmpty( $duplicate->get_meta_data() ); } }