adding test_datasets compat with pretraining_dataset (streaming) (#2206) [skip ci]

src/axolotl/utils/data/sft.py

@@ -85,6 +85,7 @@ def prepare_dataset(cfg, tokenizer, processor=None):
                     processor=processor,
                 )
     else:
+        # Load streaming dataset if pretraining_dataset is given
         path = cfg.pretraining_dataset
         split = "train"
         name = None
@@ -116,7 +117,18 @@ def prepare_dataset(cfg, tokenizer, processor=None):
         )
         # https://discuss.huggingface.co/t/how-to-use-huggingface-trainer-streaming-datasets-without-wrapping-it-with-torchdatas-iterablewrapper/25230
         train_dataset = train_dataset.with_format("torch")
+
+        # Load eval dataset (non-streaming) if specified
         eval_dataset = None
+        if cfg.test_datasets:
+            _, eval_dataset, _ = load_prepare_datasets(
+                tokenizer,
+                cfg,
+                DEFAULT_DATASET_PREPARED_PATH,
+                split="test",
+                processor=processor,
+            )
+
         if cfg.dataset_exact_deduplication:
             LOG.info("Deduplication not available for pretrained datasets")