Sanity Check via a second condition

tests/test_mixture.py

@@ -90,6 +90,20 @@ async def test_mixture_dataset_simulated_data_size():
         assert len(batch) == 3
         assert all(item in [1, 10, 100] for item in batch)
 
+    mixture_ds = MixtureDataset(
+        datasets(),
+        weights,
+        block_size=10,
+        key=key(),
+        randomize_blocks=False,
+        stop_strategy=StopStrategy.RESTART_STRATEGY,
+        simulated_data_ratio=0.4,
+    )
+    for _ in range(10):
+        batch = await mixture_ds.get_batch([0, 1, 2])
+        assert len(batch) == 3
+        assert all(item in [1, 2, 10, 20, 100, 200] for item in batch)
+
 
 @pytest.mark.asyncio
 async def test_mixture_dataset_normalized_weights():