Get the segment size parameter right

integration/test_vectors.py

@@ -57,9 +57,9 @@ async def skiptest_generate(reactor, request, alice):
     ever-changing set of outputs.
     """
     space = starmap(
-        # segmentSize could be a parameter someday but it's not easy to vary
+        # segment_size could be a parameter someday but it's not easy to vary
         # using the Python implementation so it isn't one for now.
-        partial(vectors.Case, segmentSize=parameters.SEGMENT_SIZE),
+        partial(vectors.Case, segment_size=parameters.SEGMENT_SIZE),
         product(
             parameters.ZFEC_PARAMS,
             parameters.CONVERGENCE_SECRETS,

integration/vectors/vectors.py

@@ -29,10 +29,10 @@ class Case:
     Represent one case for which we want/have a test vector.
     """
     seed_params: Param
-    segment_size: int
     convergence: bytes
     seed_data: Sample
     fmt: CHK | SSK
+    segment_size: int
 
     @property
     def data(self):