Strictly enforce instance attrs in critical functional test classes.

Additionally, removed redundant parentheses and added PEP-8 compliant
spacing around those classes.

2 files changed, 138 insertions, 44 deletions

diff --git a/test/functional/test_framework/messages.py b/test/functional/test_framework/messages.py
index 0a3907cba4..8e9372767d 100755
--- a/test/functional/test_framework/messages.py
+++ b/test/functional/test_framework/messages.py
@@ -13,7 +13,11 @@ CBlock, CTransaction, CBlockHeader, CTxIn, CTxOut, etc....:
 msg_block, msg_tx, msg_headers, etc.:
     data structures that represent network messages
 
-ser_*, deser_*: functions that handle serialization/deserialization."""
+ser_*, deser_*: functions that handle serialization/deserialization.
+
+Classes use __slots__ to ensure extraneous attributes aren't accidentally added
+by tests, compromising their intended effect.
+"""
 from codecs import encode
 import copy
 import hashlib
@@ -185,7 +189,10 @@ def ToHex(obj):
 
 # Objects that map to bitcoind objects, which can be serialized/deserialized
 
-class CAddress():
+
+class CAddress:
+    __slots__ = ("ip", "nServices", "pchReserved", "port", "time")
+
     def __init__(self):
         self.time = 0
         self.nServices = 1
@@ -215,7 +222,10 @@ class CAddress():
         return "CAddress(nServices=%i ip=%s port=%i)" % (self.nServices,
                                                          self.ip, self.port)
 
-class CInv():
+
+class CInv:
+    __slots__ = ("hash", "type")
+
     typemap = {
         0: "Error",
         1: "TX",
@@ -244,7 +254,9 @@ class CInv():
             % (self.typemap[self.type], self.hash)
 
 
-class CBlockLocator():
+class CBlockLocator:
+    __slots__ = ("nVersion", "vHave")
+
     def __init__(self):
         self.nVersion = MY_VERSION
         self.vHave = []
@@ -264,7 +276,9 @@ class CBlockLocator():
             % (self.nVersion, repr(self.vHave))
 
 
-class COutPoint():
+class COutPoint:
+    __slots__ = ("hash", "n")
+
     def __init__(self, hash=0, n=0):
         self.hash = hash
         self.n = n
@@ -283,7 +297,9 @@ class COutPoint():
         return "COutPoint(hash=%064x n=%i)" % (self.hash, self.n)
 
 
-class CTxIn():
+class CTxIn:
+    __slots__ = ("nSequence", "prevout", "scriptSig")
+
     def __init__(self, outpoint=None, scriptSig=b"", nSequence=0):
         if outpoint is None:
             self.prevout = COutPoint()
@@ -311,7 +327,9 @@ class CTxIn():
                self.nSequence)
 
 
-class CTxOut():
+class CTxOut:
+    __slots__ = ("nValue", "scriptPubKey")
+
     def __init__(self, nValue=0, scriptPubKey=b""):
         self.nValue = nValue
         self.scriptPubKey = scriptPubKey
@@ -332,7 +350,9 @@ class CTxOut():
                bytes_to_hex_str(self.scriptPubKey))
 
 
-class CScriptWitness():
+class CScriptWitness:
+    __slots__ = ("stack",)
+
     def __init__(self):
         # stack is a vector of strings
         self.stack = []
@@ -347,7 +367,9 @@ class CScriptWitness():
         return True
 
 
-class CTxInWitness():
+class CTxInWitness:
+    __slots__ = ("scriptWitness",)
+
     def __init__(self):
         self.scriptWitness = CScriptWitness()
 
@@ -364,7 +386,9 @@ class CTxInWitness():
         return self.scriptWitness.is_null()
 
 
-class CTxWitness():
+class CTxWitness:
+    __slots__ = ("vtxinwit",)
+
     def __init__(self):
         self.vtxinwit = []
 
@@ -392,7 +416,10 @@ class CTxWitness():
         return True
 
 
-class CTransaction():
+class CTransaction:
+    __slots__ = ("hash", "nLockTime", "nVersion", "sha256", "vin", "vout",
+                 "wit")
+
     def __init__(self, tx=None):
         if tx is None:
             self.nVersion = 1
@@ -496,7 +523,10 @@ class CTransaction():
             % (self.nVersion, repr(self.vin), repr(self.vout), repr(self.wit), self.nLockTime)
 
 
-class CBlockHeader():
+class CBlockHeader:
+    __slots__ = ("hash", "hashMerkleRoot", "hashPrevBlock", "nBits", "nNonce",
+                 "nTime", "nVersion", "sha256")
+
     def __init__(self, header=None):
         if header is None:
             self.set_null()
@@ -565,6 +595,8 @@ class CBlockHeader():
 
 
 class CBlock(CBlockHeader):
+    __slots__ = ("vtx",)
+
     def __init__(self, header=None):
         super(CBlock, self).__init__(header)
         self.vtx = []
@@ -636,7 +668,9 @@ class CBlock(CBlockHeader):
                time.ctime(self.nTime), self.nBits, self.nNonce, repr(self.vtx))
 
 
-class PrefilledTransaction():
+class PrefilledTransaction:
+    __slots__ = ("index", "tx")
+
     def __init__(self, index=0, tx = None):
         self.index = index
         self.tx = tx
@@ -664,8 +698,12 @@ class PrefilledTransaction():
     def __repr__(self):
         return "PrefilledTransaction(index=%d, tx=%s)" % (self.index, repr(self.tx))
 
+
 # This is what we send on the wire, in a cmpctblock message.
-class P2PHeaderAndShortIDs():
+class P2PHeaderAndShortIDs:
+    __slots__ = ("header", "nonce", "prefilled_txn", "prefilled_txn_length",
+                 "shortids", "shortids_length")
+
     def __init__(self):
         self.header = CBlockHeader()
         self.nonce = 0
@@ -703,9 +741,11 @@ class P2PHeaderAndShortIDs():
     def __repr__(self):
         return "P2PHeaderAndShortIDs(header=%s, nonce=%d, shortids_length=%d, shortids=%s, prefilled_txn_length=%d, prefilledtxn=%s" % (repr(self.header), self.nonce, self.shortids_length, repr(self.shortids), self.prefilled_txn_length, repr(self.prefilled_txn))
 
+
 # P2P version of the above that will use witness serialization (for compact
 # block version 2)
 class P2PHeaderAndShortWitnessIDs(P2PHeaderAndShortIDs):
+    __slots__ = ()
     def serialize(self):
         return super(P2PHeaderAndShortWitnessIDs, self).serialize(with_witness=True)
 
@@ -715,9 +755,12 @@ def calculate_shortid(k0, k1, tx_hash):
     expected_shortid &= 0x0000ffffffffffff
     return expected_shortid
 
+
 # This version gets rid of the array lengths, and reinterprets the differential
 # encoding into indices that can be used for lookup.
-class HeaderAndShortIDs():
+class HeaderAndShortIDs:
+    __slots__ = ("header", "nonce", "prefilled_txn", "shortids", "use_witness")
+
     def __init__(self, p2pheaders_and_shortids = None):
         self.header = CBlockHeader()
         self.nonce = 0
@@ -778,7 +821,8 @@ class HeaderAndShortIDs():
         return "HeaderAndShortIDs(header=%s, nonce=%d, shortids=%s, prefilledtxn=%s" % (repr(self.header), self.nonce, repr(self.shortids), repr(self.prefilled_txn))
 
 
-class BlockTransactionsRequest():
+class BlockTransactionsRequest:
+    __slots__ = ("blockhash", "indexes")
 
     def __init__(self, blockhash=0, indexes = None):
         self.blockhash = blockhash
@@ -818,7 +862,8 @@ class BlockTransactionsRequest():
         return "BlockTransactionsRequest(hash=%064x indexes=%s)" % (self.blockhash, repr(self.indexes))
 
 
-class BlockTransactions():
+class BlockTransactions:
+    __slots__ = ("blockhash", "transactions")
 
     def __init__(self, blockhash=0, transactions = None):
         self.blockhash = blockhash
@@ -840,7 +885,10 @@ class BlockTransactions():
     def __repr__(self):
         return "BlockTransactions(hash=%064x transactions=%s)" % (self.blockhash, repr(self.transactions))
 
-class CPartialMerkleTree():
+
+class CPartialMerkleTree:
+    __slots__ = ("fBad", "nTransactions", "vBits", "vHash")
+
     def __init__(self):
         self.nTransactions = 0
         self.vHash = []
@@ -868,7 +916,10 @@ class CPartialMerkleTree():
     def __repr__(self):
         return "CPartialMerkleTree(nTransactions=%d, vHash=%s, vBits=%s)" % (self.nTransactions, repr(self.vHash), repr(self.vBits))
 
-class CMerkleBlock():
+
+class CMerkleBlock:
+    __slots__ = ("header", "txn")
+
     def __init__(self):
         self.header = CBlockHeader()
         self.txn = CPartialMerkleTree()
@@ -888,7 +939,9 @@ class CMerkleBlock():
 
 
 # Objects that correspond to messages on the wire
-class msg_version():
+class msg_version:
+    __slots__ = ("addrFrom", "addrTo", "nNonce", "nRelay", "nServices",
+                 "nStartingHeight", "nTime", "nVersion", "strSubVer")
     command = b"version"
 
     def __init__(self):
@@ -945,7 +998,8 @@ class msg_version():
                self.strSubVer, self.nStartingHeight, self.nRelay)
 
 
-class msg_verack():
+class msg_verack:
+    __slots__ = ()
     command = b"verack"
 
     def __init__(self):
@@ -961,7 +1015,8 @@ class msg_verack():
         return "msg_verack()"
 
 
-class msg_addr():
+class msg_addr:
+    __slots__ = ("addrs",)
     command = b"addr"
 
     def __init__(self):
@@ -977,7 +1032,8 @@ class msg_addr():
         return "msg_addr(addrs=%s)" % (repr(self.addrs))
 
 
-class msg_inv():
+class msg_inv:
+    __slots__ = ("inv",)
     command = b"inv"
 
     def __init__(self, inv=None):
@@ -996,7 +1052,8 @@ class msg_inv():
         return "msg_inv(inv=%s)" % (repr(self.inv))
 
 
-class msg_getdata():
+class msg_getdata:
+    __slots__ = ("inv",)
     command = b"getdata"
 
     def __init__(self, inv=None):
@@ -1012,7 +1069,8 @@ class msg_getdata():
         return "msg_getdata(inv=%s)" % (repr(self.inv))
 
 
-class msg_getblocks():
+class msg_getblocks:
+    __slots__ = ("locator", "hashstop")
     command = b"getblocks"
 
     def __init__(self):
@@ -1035,7 +1093,8 @@ class msg_getblocks():
             % (repr(self.locator), self.hashstop)
 
 
-class msg_tx():
+class msg_tx:
+    __slots__ = ("tx",)
     command = b"tx"
 
     def __init__(self, tx=CTransaction()):
@@ -1050,13 +1109,16 @@ class msg_tx():
     def __repr__(self):
         return "msg_tx(tx=%s)" % (repr(self.tx))
 
+
 class msg_witness_tx(msg_tx):
+    __slots__ = ()
 
     def serialize(self):
         return self.tx.serialize_with_witness()
 
 
-class msg_block():
+class msg_block:
+    __slots__ = ("block",)
     command = b"block"
 
     def __init__(self, block=None):
@@ -1074,9 +1136,12 @@ class msg_block():
     def __repr__(self):
         return "msg_block(block=%s)" % (repr(self.block))
 
+
 # for cases where a user needs tighter control over what is sent over the wire
 # note that the user must supply the name of the command, and the data
-class msg_generic():
+class msg_generic:
+    __slots__ = ("command", "data")
+
     def __init__(self, command, data=None):
         self.command = command
         self.data = data
@@ -1087,13 +1152,16 @@ class msg_generic():
     def __repr__(self):
         return "msg_generic()"
 
-class msg_witness_block(msg_block):
 
+class msg_witness_block(msg_block):
+    __slots__ = ()
     def serialize(self):
         r = self.block.serialize(with_witness=True)
         return r
 
-class msg_getaddr():
+
+class msg_getaddr:
+    __slots__ = ()
     command = b"getaddr"
 
     def __init__(self):
@@ -1109,7 +1177,8 @@ class msg_getaddr():
         return "msg_getaddr()"
 
 
-class msg_ping():
+class msg_ping:
+    __slots__ = ("nonce",)
     command = b"ping"
 
     def __init__(self, nonce=0):
@@ -1127,7 +1196,8 @@ class msg_ping():
         return "msg_ping(nonce=%08x)" % self.nonce
 
 
-class msg_pong():
+class msg_pong:
+    __slots__ = ("nonce",)
     command = b"pong"
 
     def __init__(self, nonce=0):
@@ -1145,7 +1215,8 @@ class msg_pong():
         return "msg_pong(nonce=%08x)" % self.nonce
 
 
-class msg_mempool():
+class msg_mempool:
+    __slots__ = ()
     command = b"mempool"
 
     def __init__(self):
@@ -1160,7 +1231,9 @@ class msg_mempool():
     def __repr__(self):
         return "msg_mempool()"
 
-class msg_sendheaders():
+
+class msg_sendheaders:
+    __slots__ = ()
     command = b"sendheaders"
 
     def __init__(self):
@@ -1180,7 +1253,8 @@ class msg_sendheaders():
 # number of entries
 # vector of hashes
 # hash_stop (hash of last desired block header, 0 to get as many as possible)
-class msg_getheaders():
+class msg_getheaders:
+    __slots__ = ("hashstop", "locator",)
     command = b"getheaders"
 
     def __init__(self):
@@ -1205,7 +1279,8 @@ class msg_getheaders():
 
 # headers message has
 # <count> <vector of block headers>
-class msg_headers():
+class msg_headers:
+    __slots__ = ("headers",)
     command = b"headers"
 
     def __init__(self, headers=None):
@@ -1225,7 +1300,8 @@ class msg_headers():
         return "msg_headers(headers=%s)" % repr(self.headers)
 
 
-class msg_reject():
+class msg_reject:
+    __slots__ = ("code", "data", "message", "reason")
     command = b"reject"
     REJECT_MALFORMED = 1
 
@@ -1256,7 +1332,9 @@ class msg_reject():
         return "msg_reject: %s %d %s [%064x]" \
             % (self.message, self.code, self.reason, self.data)
 
-class msg_feefilter():
+
+class msg_feefilter:
+    __slots__ = ("feerate",)
     command = b"feefilter"
 
     def __init__(self, feerate=0):
@@ -1273,7 +1351,9 @@ class msg_feefilter():
     def __repr__(self):
         return "msg_feefilter(feerate=%08x)" % self.feerate
 
-class msg_sendcmpct():
+
+class msg_sendcmpct:
+    __slots__ = ("announce", "version")
     command = b"sendcmpct"
 
     def __init__(self):
@@ -1293,7 +1373,9 @@ class msg_sendcmpct():
     def __repr__(self):
         return "msg_sendcmpct(announce=%s, version=%lu)" % (self.announce, self.version)
 
-class msg_cmpctblock():
+
+class msg_cmpctblock:
+    __slots__ = ("header_and_shortids",)
     command = b"cmpctblock"
 
     def __init__(self, header_and_shortids = None):
@@ -1311,7 +1393,9 @@ class msg_cmpctblock():
     def __repr__(self):
         return "msg_cmpctblock(HeaderAndShortIDs=%s)" % repr(self.header_and_shortids)
 
-class msg_getblocktxn():
+
+class msg_getblocktxn:
+    __slots__ = ("block_txn_request",)
     command = b"getblocktxn"
 
     def __init__(self):
@@ -1329,7 +1413,9 @@ class msg_getblocktxn():
     def __repr__(self):
         return "msg_getblocktxn(block_txn_request=%s)" % (repr(self.block_txn_request))
 
-class msg_blocktxn():
+
+class msg_blocktxn:
+    __slots__ = ("block_transactions",)
     command = b"blocktxn"
 
     def __init__(self):
@@ -1346,7 +1432,10 @@ class msg_blocktxn():
     def __repr__(self):
         return "msg_blocktxn(block_transactions=%s)" % (repr(self.block_transactions))
 
+
 class msg_witness_blocktxn(msg_blocktxn):
+    __slots__ = ()
+
     def serialize(self):
         r = b""
         r += self.block_transactions.serialize(with_witness=True)
diff --git a/test/functional/test_framework/script.py b/test/functional/test_framework/script.py
index 375d6334f7..2fe44010ba 100644
--- a/test/functional/test_framework/script.py
+++ b/test/functional/test_framework/script.py
@@ -26,7 +26,7 @@ def hash160(s):
 _opcode_instances = []
 class CScriptOp(int):
     """A single script opcode"""
-    __slots__ = []
+    __slots__ = ()
 
     @staticmethod
     def encode_op_pushdata(d):
@@ -361,8 +361,11 @@ class CScriptTruncatedPushDataError(CScriptInvalidError):
         self.data = data
         super(CScriptTruncatedPushDataError, self).__init__(msg)
 
+
 # This is used, eg, for blockchain heights in coinbase scripts (bip34)
-class CScriptNum():
+class CScriptNum:
+    __slots__ = ("value",)
+
     def __init__(self, d=0):
         self.value = d
 
@@ -393,6 +396,8 @@ class CScript(bytes):
 
     iter(script) however does iterate by opcode.
     """
+    __slots__ = ()
+
     @classmethod
     def __coerce_instance(cls, other):
         # Coerce other into bytes