@sgugger what would you think we create 2 additional methods in fakes.py called fake_text_data and fake_image_data. Then for e.g. fake_text_data would open and load a dummy file (like in test_text_data) and use that class to test one_item and other fastai functions that would not work with a TensorDataset. I.o.w. in test_basic_data I use fake_data, which uses TensorDataset to test e.g. one_batch. But other functions like one_item we test from test_text_data.
Or we find a way to create fake_data with not just TensorDataset but rather fast.ai functions - but not sure how - to do that.