function test_update()
 {
     //arrange
     $stylist_name = "Nora";
     $id = null;
     $test_stylist = new Stylist($stylist_name, $id);
     $test_stylist->save();
     $new_stylist_name = "Dora";
     //act
     $test_stylist->updateStylistName($new_stylist_name);
     //assert
     $this->assertEquals("Dora", $test_stylist->getStylistName());
 }