function testUpdateBookId()
{
//Arrange
$book_id = 1;
$test_copy = new Copy($book_id);
$test_copy->save();
$new_book_id = 3;
//Act
$test_copy->updateBookId($new_book_id);
//Assert
$this->assertEquals($test_copy->getBookId(), $new_book_id);
}
