Preserve RNG state in dataset iteration

src/art/utils/iterate_dataset.py

@@ -62,8 +62,7 @@ def iterate_dataset(
     for epoch in range(num_epochs):
         # Create indices and shuffle deterministically based on epoch
         indices = list(range(dataset_size))
-        random.seed(epoch)  # Ensure shuffling is the same for a given epoch
-        random.shuffle(indices)
+        random.Random(epoch).shuffle(indices)
 
         for i in range(0, dataset_size, groups_per_step):
             epoch_step = i // groups_per_step

tests/unit/test_iterate_dataset.py

@@ -0,0 +1,36 @@
+import random
+
+from art.utils.iterate_dataset import iterate_dataset
+
+
+def test_iterate_dataset_is_deterministic_across_runs() -> None:
+    dataset = list(range(10))
+
+    first = [
+        batch.items
+        for batch in iterate_dataset(
+            dataset, groups_per_step=3, num_epochs=2, use_tqdm=False
+        )
+    ]
+    second = [
+        batch.items
+        for batch in iterate_dataset(
+            dataset, groups_per_step=3, num_epochs=2, use_tqdm=False
+        )
+    ]
+
+    assert first == second
+
+
+def test_iterate_dataset_does_not_reset_global_random_state() -> None:
+    dataset = list(range(10))
+
+    random.seed(12345)
+    expected = [random.random() for _ in range(3)]
+
+    random.seed(12345)
+    iterator = iterate_dataset(dataset, groups_per_step=2, num_epochs=2, use_tqdm=False)
+    next(iterator)
+    after_iteration = [random.random() for _ in range(3)]
+
+    assert after_iteration == expected