function testUpdateDueDate()
{
//Arrange
$book_id = 1;
$due_date = "2015-12-12";
$test_copy = new Copy($book_id, $due_date);
$test_copy->save();
$new_due_date = "2012-21-21";
//Act
$test_copy->updateDueDate($new_due_date);
//Assert
$this->assertEquals($test_copy->getDueDate(), $new_due_date);
}
