pl.trainer.test() does not have len() for IterableDataset

[lixsh6]

I got a similar problem with #3500
MyDataset is a IterableDataset, but it does not work in pl.trainer.test() since it's not accessible to measure its length.

Traceback (most recent call last):
  File "inference.py", line 57, in <module>
    trainer.test(model, test_dataloaders=valid_data_loader)
  File "/usr/local/lib/python3.6/dist-packages/pytorch_lightning/trainer/trainer.py", line 914, in test
    if test_dataloaders and datamodule:
  File "/usr/local/lib/python3.6/dist-packages/torch/utils/data/dataloader.py", line 388, in __len__
    length = self._IterableDataset_len_called = len(self.dataset)  # type: ignore
TypeError: object of type 'MyDataset' has no len()

Anybody helps me for this? Thank you very much!

[awaelchli]

Hi, have a look here, I'm working on a fix:
#6828

[lixsh6]

Thanks for your quick fix！！！