fixed typo (huggingface#10861)

src/transformers/trainer.py

@@ -1722,7 +1722,7 @@ def evaluate(
         return output.metrics
 
     def predict(
-        self, test_dataset: Dataset, ignore_keys: Optional[List[str]] = None, metric_key_prefix: str = "eval"
+        self, test_dataset: Dataset, ignore_keys: Optional[List[str]] = None, metric_key_prefix: str = "test"
     ) -> PredictionOutput:
         """
         Run prediction and returns predictions and potential metrics.
@@ -1737,9 +1737,9 @@ def predict(
             ignore_keys (:obj:`Lst[str]`, `optional`):
                 A list of keys in the output of your model (if it is a dictionary) that should be ignored when
                 gathering predictions.
-            metric_key_prefix (:obj:`str`, `optional`, defaults to :obj:`"eval"`):
+            metric_key_prefix (:obj:`str`, `optional`, defaults to :obj:`"test"`):
                 An optional prefix to be used as the metrics key prefix. For example the metrics "bleu" will be named
-                "eval_bleu" if the prefix is "eval" (default)
+                "test_bleu" if the prefix is "test" (default)
 
         .. note::