ATDD, Gherkin, Specflow approach, blackbox testing issue

I am trying to get some experience in developing outside in with ATDD and now i got my first roadblock.

The application is a simple desktop application (wpf) which should be able to search the filesystem for duplicates.

The first feature i want to implement is to customize the directories which should be searched. But i dont know how i should test that feature end to end.

Would it be a good automated approach to create a test directory with 2 files (duplicates), then select that directory over the user interface then start the search and validate that the result are the 2 created files ?

I would be testing a lot more then simply the feature to specifiy the search directories.

Feature: CustomizeSearchDirectories

In order to speed up and better control the search

As a customer

I want to customize the directories which will be searched

thanks for feedback that can reduce my confusion