Uploading a file through a browser seems more of a browser feature that many web application use. In the sense that it is a browser feature, it may not need testing. I see your challenge as one in testability. That is, your test requires information from a CSV file.
If the application is designed well, it should not care how the file is presented. Is it possible to isolate the functionality so that the uploading step is not needed? In that manner, you can evaluate the important part of the application functionality separate from browser features.