test: Remove struct.pack from almost all places

contrib/seeds/generate-seeds.py

@@ -29,7 +29,6 @@ These should be pasted into `src/chainparamsseeds.h`.
 
 from base64 import b32decode
 from enum import Enum
-import struct
 import sys
 import os
 import re
@@ -117,11 +116,11 @@ def ser_compact_size(l):
     if l < 253:
         r = l.to_bytes(1, "little")
     elif l < 0x10000:
-        r = struct.pack("<BH", 253, l)
+        r = (253).to_bytes(1, "little") + l.to_bytes(2, "little")
     elif l < 0x100000000:
-        r = struct.pack("<BI", 254, l)
+        r = (254).to_bytes(1, "little") + l.to_bytes(4, "little")
     else:
-        r = struct.pack("<BQ", 255, l)
+        r = (255).to_bytes(1, "little") + l.to_bytes(8, "little")
     return r
 
 def bip155_serialize(spec):

test/functional/feature_addrman.py

@@ -6,7 +6,6 @@
 
 import os
 import re
-import struct
 
 from test_framework.messages import ser_uint256, hash256, MAGIC_BYTES
 from test_framework.netutil import ADDRMAN_NEW_BUCKET_COUNT, ADDRMAN_TRIED_BUCKET_COUNT, ADDRMAN_BUCKET_SIZE

test/functional/feature_block.py

@@ -4,7 +4,6 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test block processing."""
 import copy
-import struct
 import time
 
 from test_framework.blocktools import (
@@ -67,7 +66,7 @@ class CBrokenBlock(CBlock):
     def serialize(self, with_witness=False):
         r = b""
         r += super(CBlock, self).serialize()
-        r += struct.pack("<BQ", 255, len(self.vtx))
+        r += (255).to_bytes(1, "little") + len(self.vtx).to_bytes(8, "little")
         for tx in self.vtx:
             if with_witness:
                 r += tx.serialize_with_witness()

test/functional/p2p_segwit.py

@@ -5,7 +5,6 @@
 """Test segwit transactions and blocks on P2P network."""
 from decimal import Decimal
 import random
-import struct
 import time
 
 from test_framework.blocktools import (

test/functional/test_framework/script.py

@@ -8,7 +8,6 @@ This file is modified from python-bitcoinlib.
 """
 
 from collections import namedtuple
-import struct
 import unittest
 
 from .key import TaggedHash, tweak_add_pubkey, compute_xonly_pubkey