fix test_weight_checker_comparator assertion and ue8m0 scale unpack (#29623)

python/sglang/srt/utils/weight_checker_comparator.py

@@ -59,6 +59,8 @@ class Fp8BlockComparable(ComparableWeight):
     def _normalize_scale(w_q: torch.Tensor, w_s: torch.Tensor) -> torch.Tensor:
         if w_s.dtype == torch.int32:
             w_s = inverse_transform_scale_ue8m0(w_s, mn=w_q.shape[-2])
+            # ue8m0 packing aligns k to a multiple of 4; drop the padding blocks.
+            w_s = w_s[..., : -(-w_q.shape[-1] // 128)]
         return w_s.to(torch.float32)
 
     @staticmethod

test/registered/unit/utils/test_weight_checker_comparator.py

@@ -133,7 +133,10 @@ class TestCompareQuantPair(CustomTestCase):
         reference = _compare_quant_pair(self.e_q, self.e_s, self.a_q, self.a_s)
         with patch("sglang.srt.utils.weight_checker_comparator.CHUNK_NUMEL", 128 * 128):
             chunked = _compare_quant_pair(self.e_q, self.e_s, self.a_q, self.a_s)
-        self.assertEqual(chunked, reference)
+        eq_c, max_c, mean_c, ex_c = chunked
+        eq_r, max_r, mean_r, ex_r = reference
+        self.assertEqual((eq_c, max_c, ex_c), (eq_r, max_r, ex_r))
+        self.assertAlmostEqual(mean_c, mean_r, places=7)
 
     @staticmethod
     def _quantize_partial(weight: torch.Tensor, scale_margin: float):