Fix Rand.u8() to return unsigned integers

Existing test vector generators are adjusted to use Rand.i8() so they
generate the same test vectors. We should evaluate these later to
determine whether they should actually use Rand.u8() (and update the
test vectors across the ecosystem).

transaction.py

@@ -155,7 +155,7 @@ RAND_OPCODES = [
 class Script(object):
     def __init__(self, rand):
         self._script = bytes([
-            rand.a(RAND_OPCODES) for i in range(rand.u8() % 10)
+            rand.a(RAND_OPCODES) for i in range(rand.i8() % 10)
         ])
 
     def raw(self):
@@ -212,11 +212,11 @@ class Transaction(object):
             self.nVersion = rand.u32() & ((1 << 31) - 1)
 
         self.vin = []
-        for i in range(rand.u8() % 3):
+        for i in range(rand.i8() % 3):
             self.vin.append(TxIn(rand))
 
         self.vout = []
-        for i in range(rand.u8() % 3):
+        for i in range(rand.i8() % 3):
             self.vout.append(TxOut(rand))
 
         self.nLockTime = rand.u32()
@@ -227,14 +227,14 @@ class Transaction(object):
         self.vShieldedSpends = []
         self.vShieldedOutputs = []
         if self.nVersion >= SAPLING_TX_VERSION:
-            for _ in range(rand.u8() % 5):
+            for _ in range(rand.i8() % 5):
                 self.vShieldedSpends.append(SpendDescription(rand))
-            for _ in range(rand.u8() % 5):
+            for _ in range(rand.i8() % 5):
                 self.vShieldedOutputs.append(OutputDescription(rand))
 
         self.vJoinSplit = []
         if self.nVersion >= 2:
-            for i in range(rand.u8() % 3):
+            for i in range(rand.i8() % 3):
                 self.vJoinSplit.append(JoinSplit(rand, self.fOverwintered and self.nVersion >= SAPLING_TX_VERSION))
             if len(self.vJoinSplit) > 0:
                 self.joinSplitPubKey = rand.b(32) # Potentially invalid

tv_rand.py

@@ -12,9 +12,12 @@ class Rand(object):
     def v(self, l, f):
         return struct.unpack(f, self.b(l))[0]
 
-    def u8(self):
+    def i8(self):
         return self.v(1, 'b')
 
+    def u8(self):
+        return self.v(1, 'B')
+
     def u32(self):
         return self.v(4, '<I')
 

zip_0143.py

@@ -113,7 +113,7 @@ def main():
     for i in range(10):
         tx = Transaction(rand, OVERWINTER_TX_VERSION)
         scriptCode = Script(rand)
-        nIn = rand.u8() % (len(tx.vin) + 1)
+        nIn = rand.i8() % (len(tx.vin) + 1)
         if nIn == len(tx.vin):
             nIn = NOT_AN_INPUT
         nHashType = SIGHASH_ALL if nIn == NOT_AN_INPUT else rand.a([

zip_0243.py

@@ -120,7 +120,7 @@ def main():
     for _ in range(10):
         tx = Transaction(rand, SAPLING_TX_VERSION)
         scriptCode = Script(rand)
-        nIn = rand.u8() % (len(tx.vin) + 1)
+        nIn = rand.i8() % (len(tx.vin) + 1)
         if nIn == len(tx.vin):
             nIn = NOT_AN_INPUT
         nHashType = SIGHASH_ALL if nIn == NOT_AN_INPUT else rand.a([