tests: functional tests for Schnorr/Taproot/Tapscript

A large functional test is added that automatically generates random transactions which
exercise various aspects of the new rules, and verifies they are accepted into the mempool
(when appropriate), and correctly accepted/rejected in (Python-constructed) blocks.

Includes sighashing code and many tests by Johnson Lau.
Includes a test by Matthew Zipkin.
Includes several tests and improvements by Greg Sanders.

1 files changed, 15 insertions, 4 deletions

diff --git a/test/functional/test_framework/blocktools.py b/test/functional/test_framework/blocktools.py
index afc1995009..4be8b7d80b 100644
--- a/test/functional/test_framework/blocktools.py
+++ b/test/functional/test_framework/blocktools.py
@@ -43,7 +43,9 @@ from .script import (
 from .util import assert_equal
 from io import BytesIO
 
+WITNESS_SCALE_FACTOR = 4
 MAX_BLOCK_SIGOPS = 20000
+MAX_BLOCK_SIGOPS_WEIGHT = MAX_BLOCK_SIGOPS * WITNESS_SCALE_FACTOR
 
 # Genesis block time (regtest)
 TIME_GENESIS_BLOCK = 1296688602
@@ -101,22 +103,31 @@ def script_BIP34_coinbase_height(height):
     return CScript([CScriptNum(height)])
 
 
-def create_coinbase(height, pubkey=None):
-    """Create a coinbase transaction, assuming no miner fees.
+def create_coinbase(height, pubkey=None, extra_output_script=None, fees=0):
+    """Create a coinbase transaction.
 
     If pubkey is passed in, the coinbase output will be a P2PK output;
-    otherwise an anyone-can-spend output."""
+    otherwise an anyone-can-spend output.
+
+    If extra_output_script is given, make a 0-value output to that
+    script. This is useful to pad block weight/sigops as needed. """
     coinbase = CTransaction()
     coinbase.vin.append(CTxIn(COutPoint(0, 0xffffffff), script_BIP34_coinbase_height(height), 0xffffffff))
     coinbaseoutput = CTxOut()
     coinbaseoutput.nValue = 50 * COIN
     halvings = int(height / 150)  # regtest
     coinbaseoutput.nValue >>= halvings
-    if (pubkey is not None):
+    coinbaseoutput.nValue += fees
+    if pubkey is not None:
         coinbaseoutput.scriptPubKey = CScript([pubkey, OP_CHECKSIG])
     else:
         coinbaseoutput.scriptPubKey = CScript([OP_TRUE])
     coinbase.vout = [coinbaseoutput]
+    if extra_output_script is not None:
+        coinbaseoutput2 = CTxOut()
+        coinbaseoutput2.nValue = 0
+        coinbaseoutput2.scriptPubKey = extra_output_script
+        coinbase.vout.append(coinbaseoutput2)
     coinbase.calc_sha256()
     return coinbase