How to reliable test file reader/writer?

So I am working on project. It has reader/writer components and there is increasing number of developer creating new components. My question is, how to efficiently and automatically test reader/writer components?

As far as I know, there is no such effective way to mock up files for testing, because our files are big data files. Tons of records in one file. So simple unit testing is out of discussion I suppose. Is there some testing framework, which can help with this?