test: cover testnet4 magic in assumeutxo.py

Replace testnet3 and use MAGIC_BYTES constants.

test/functional/feature_assumeutxo.py

@@ -23,10 +23,11 @@ from test_framework.compressor import (
 from test_framework.messages import (
     CBlockHeader,
     from_hex,
-    msg_headers,
-    tx_from_hex,
-    ser_varint,
+    MAGIC_BYTES,
     MAX_MONEY,
+    msg_headers,
+    ser_varint,
+    tx_from_hex,
 )
 from test_framework.p2p import (
     P2PInterface,
@@ -102,15 +103,15 @@ class AssumeutxoTest(BitcoinTestFramework):
         self.log.info("  - snapshot file with mismatching network magic")
         invalid_magics = [
             # magic, name, real
-            [0xf9beb4d9, "main", True],
-            [0x0b110907, "test", True],
-            [0x0a03cf40, "signet", True],
-            [0x00000000, "", False],
-            [0xffffffff, "", False],
+            [MAGIC_BYTES["mainnet"], "main", True],
+            [MAGIC_BYTES["testnet4"], "testnet4", True],
+            [MAGIC_BYTES["signet"], "signet", True],
+            [0x00000000.to_bytes(4, 'big'), "", False],
+            [0xffffffff.to_bytes(4, 'big'), "", False],
         ]
         for [magic, name, real] in invalid_magics:
             with open(bad_snapshot_path, 'wb') as f:
-                f.write(valid_snapshot_contents[:7] + magic.to_bytes(4, 'big') + valid_snapshot_contents[11:])
+                f.write(valid_snapshot_contents[:7] + magic + valid_snapshot_contents[11:])
             if real:
                 assert_raises_rpc_error(parsing_error_code, f"Unable to parse metadata: The network of the snapshot ({name}) does not match the network of this node (regtest).", node.loadtxoutset, bad_snapshot_path)
             else:

test/functional/test_framework/messages.py

@@ -80,6 +80,7 @@ DEFAULT_MEMPOOL_EXPIRY_HOURS = 336  # hours
 MAGIC_BYTES = {
     "mainnet": b"\xf9\xbe\xb4\xd9",   # mainnet
     "testnet3": b"\x0b\x11\x09\x07",  # testnet3
+    "testnet4": b"\x1c\x16\x3f\x28",  # testnet4
     "regtest": b"\xfa\xbf\xb5\xda",   # regtest
     "signet": b"\x0a\x03\xcf\x40",    # signet
 }