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); }