Fix test_bertscore_sorting bug + validate idf arg

src/torchmetrics/functional/text/bert.py

@@ -349,11 +349,16 @@ def bert_score(
 
     """
     if len(preds) != len(target):
-        raise ValueError("Number of predicted and reference sententes must be the same!")
+        raise ValueError(
+            "Expected number of predicted and reference sententes to be the same, but got"
+            f"{len(preds)} and {len(target)}"
+        )
     if not isinstance(preds, (str, list, dict)):  # dict for BERTScore class compute call
         preds = list(preds)
     if not isinstance(target, (str, list, dict)):  # dict for BERTScore class compute call
         target = list(target)
+    if not isinstance(idf, bool):
+        raise ValueError(f"Expected argument `idf` to be a boolean, but got {idf}.")
 
     if verbose and (not _TQDM_AVAILABLE):
         raise ModuleNotFoundError(

tests/unittests/text/test_bertscore.py

@@ -174,10 +174,7 @@ def test_bertscore_differentiability(
 
 @skip_on_connection_issues()
 @pytest.mark.skipif(not _TRANSFORMERS_GREATER_EQUAL_4_4, reason="test requires transformers>4.4")
-@pytest.mark.parametrize(
-    "idf",
-    [(False,), (True,)],
-)
+@pytest.mark.parametrize("idf", [True, False])
 def test_bertscore_sorting(idf: bool):
     """Test that BERTScore is invariant to the order of the inputs."""
     short = "Short text"