[test] add get_vsize util for more programmatic testing

1 files changed, 10 insertions, 0 deletions

diff --git a/test/functional/test_framework/messages.py b/test/functional/test_framework/messages.py
index b4e609df3a..1e062ab9a4 100755
--- a/test/functional/test_framework/messages.py
+++ b/test/functional/test_framework/messages.py
@@ -22,6 +22,7 @@ from codecs import encode
 import copy
 import hashlib
 from io import BytesIO
+import math
 import random
 import socket
 import struct
@@ -67,6 +68,8 @@ MSG_WITNESS_TX = MSG_TX | MSG_WITNESS_FLAG
 
 FILTER_TYPE_BASIC = 0
 
+WITNESS_SCALE_FACTOR = 4
+
 # Serialization/deserialization tools
 def sha256(s):
     return hashlib.new('sha256', s).digest()
@@ -537,6 +540,13 @@ class CTransaction:
                 return False
         return True
 
+    # Calculate the virtual transaction size using witness and non-witness
+    # serialization size (does NOT use sigops).
+    def get_vsize(self):
+        with_witness_size = len(self.serialize_with_witness())
+        without_witness_size = len(self.serialize_without_witness())
+        return math.ceil(((WITNESS_SCALE_FACTOR - 1) * without_witness_size + with_witness_size) / WITNESS_SCALE_FACTOR)
+
     def __repr__(self):
         return "CTransaction(nVersion=%i vin=%s vout=%s wit=%s nLockTime=%i)" \
             % (self.nVersion, repr(self.vin), repr(self.vout), repr(self.wit), self.nLockTime)