Check diff in test_layerwise_casting

Author: hlky

tests/models/test_modeling_common.py

@@ -1473,7 +1473,8 @@ def test_layerwise_casting(storage_dtype, compute_dtype):
 
             # The precision test is not very important for fast tests. In most cases, the outputs will not be the same.
             # We just want to make sure that the layerwise casting is working as expected.
-            self.assertTrue(numpy_cosine_similarity_distance(base_slice, output) < 1.0)
+            diff = numpy_cosine_similarity_distance(base_slice, output)
+            self.assertTrue(diff < 1.0, f"Expected {diff=} < 1.0.")
 
         test_layerwise_casting(torch.float16, torch.float32)
         test_layerwise_casting(torch.float8_e4m3fn, torch.float32)