I plan to add tests in the next edition of the course. Existing users will get free upgrade.

Thanks for your feedback!

Thanks for reporting this. It's rather a bug in example. We'll upload the fix later this week.

Hey Mahendra,

Nice question! Here's what I think:

1. You need a class anyway, since you have to put the extracted method body somewhere. You can not put it inside interface, right?

2. You can always extract interface from a resulting class later (see Extract Interface refactoring).

Hey Nastasia,

Great question! I think they both could act as an intermediate step to a cleaner code. Here's example:

1. You have a Primitive obsession situation(say, lots of arrays). It smells bad.

2. You turn arrays into classes.

3. Now you have a lot of Data classes. Smells better, but not that good yet.

4. You add some behaviors to data classes, and merge them together if both have similar purpose.

5. Bam! Now, you've got clean code and nice classes.

Does this make sense?

Hi, Prachi!

You should always try to do just one change at time. Yes, sometimes you could cut a corner and do several small refactorings at once. But each time you do it, you're risking making an error, since your focus is spread through all the places you changed.

Here's a metaphor. Imagine a surgery operation, where a surgeon is going to cut a person's appendix. But in the process, surgeon discovers a cancer tumor and thinks "hey, I'll gonna cut this stuff as well while I'm here". And then patient dies and nobody knows whether it was because appendix or cancer.

Hope this helps!

Okay, the problem is fixed. Sorry for the inconvenience.

Thanks for reporting this, Paulo. I'm investigating the problem.