show the point also for the case of split=None

Signed-off-by: dafnapension <[email protected]>

tests/library/test_loaders.py

@@ -4,7 +4,7 @@
 from unittest.mock import patch
 
 import pandas as pd
-from datasets import IterableDataset
+from datasets import IterableDataset, IterableDatasetDict
 from unitxt.error_utils import UnitxtError
 from unitxt.loaders import (
     LoadCSV,
@@ -242,7 +242,15 @@ def test_load_HF_lazily(self):
         # now we try to touch the arriving dataset, which in current main is only done by the split generator when yielding
         with self.assertRaises(Exception):
             next(iter(dataset))
-
+        # the same goes when split=None:
+        dataset = lazy_loader.load_dataset(split=None)
+        assert isinstance(dataset, IterableDatasetDict)
+        # we just assured that load_dataset completed OK, not noticing anything bad.
+        # now we try to touch the samples in the arriving dataset, which in current main is only done by the split generator when yielding
+        with self.assertRaises(Exception):
+            for k in dataset.keys():
+                next(iter(dataset[k]))
+                break
 
     def test_load_from_HF_split(self):
         loader = LoadHF(path="sst2", split="train")