Mocking a ftp server

I want to write a test for my code which uses a ftp library and does upload data via ftp.

I would like to avoid the need for a real ftp server in my test.

What is the most simple way to test my code?

There are several edge-cases which I would like to test.

For example: my code tries to create a directory which already exists.

I want to catch the exception and do appropriate error handling.

I know that I could use the mocking library. I used it before. But maybe there is a better solution for this use case?