Test transaction selection when gbt called without segwit support

Author: sdaftuar

qa/rpc-tests/segwit.py

@@ -8,9 +8,9 @@
 from test_framework.util import *
 from test_framework.mininode import sha256, ripemd160, CTransaction, CTxIn, COutPoint, CTxOut, COIN
 from test_framework.address import script_to_p2sh, key_to_p2pkh
-from test_framework.script import CScript, OP_HASH160, OP_CHECKSIG, OP_0, hash160, OP_EQUAL, OP_DUP, OP_EQUALVERIFY, OP_1, OP_2, OP_CHECKMULTISIG, hash160
+from test_framework.script import CScript, OP_HASH160, OP_CHECKSIG, OP_0, hash160, OP_EQUAL, OP_DUP, OP_EQUALVERIFY, OP_1, OP_2, OP_CHECKMULTISIG, hash160, OP_TRUE
 from io import BytesIO
-from test_framework.mininode import FromHex, ToHex
+from test_framework.mininode import ToHex, FromHex, COIN
 
 NODE_0 = 0
 NODE_1 = 1
@@ -250,12 +250,54 @@ def run_test(self):
         assert(tmpl['transactions'][0]['txid'] == txid)
         assert(tmpl['transactions'][0]['sigops'] == 8)
 
+        self.nodes[0].generate(1) # Mine a block to clear the gbt cache
+
         self.log.info("Non-segwit miners are able to use GBT response after activation.")
-        txid = send_to_witness(1, self.nodes[0], find_unspent(self.nodes[0], 50), self.pubkey[0], False, Decimal("49.998"))
-        #assert_raises_jsonrpc(-8, "Support for 'segwit' rule requires explicit client support", self.nodes[0].getblocktemplate, {})
-        tmpl = self.nodes[0].getblocktemplate()
-        # TODO: add a transaction with witness to mempool, and verify it's not
-        # selected for mining.
+        # Create a 3-tx chain: tx1 (non-segwit input, paying to a segwit output) ->
+        #                      tx2 (segwit input, paying to a non-segwit output) ->
+        #                      tx3 (non-segwit input, paying to a non-segwit output).
+        # tx1 is allowed to appear in the block, but no others.
+        txid1 = send_to_witness(1, self.nodes[0], find_unspent(self.nodes[0], 50), self.pubkey[0], False, Decimal("49.996"))
+        hex_tx = self.nodes[0].gettransaction(txid)['hex']
+        tx = FromHex(CTransaction(), hex_tx)
+        assert(tx.wit.is_null()) # This should not be a segwit input
+        assert(txid1 in self.nodes[0].getrawmempool())
+
+        # Now create tx2, which will spend from txid1.
+        tx = CTransaction()
+        tx.vin.append(CTxIn(COutPoint(int(txid1, 16), 0), b''))
+        tx.vout.append(CTxOut(int(49.99*COIN), CScript([OP_TRUE])))
+        tx2_hex = self.nodes[0].signrawtransaction(ToHex(tx))['hex']
+        txid2 = self.nodes[0].sendrawtransaction(tx2_hex)
+        tx = FromHex(CTransaction(), tx2_hex)
+        assert(not tx.wit.is_null())
+
+        # Now create tx3, which will spend from txid2
+        tx = CTransaction()
+        tx.vin.append(CTxIn(COutPoint(int(txid2, 16), 0), b""))
+        tx.vout.append(CTxOut(int(49.95*COIN), CScript([OP_TRUE]))) # Huge fee
+        tx.calc_sha256()
+        txid3 = self.nodes[0].sendrawtransaction(ToHex(tx))
+        assert(tx.wit.is_null())
+        assert(txid3 in self.nodes[0].getrawmempool())
+
+        # Now try calling getblocktemplate() without segwit support.
+        template = self.nodes[0].getblocktemplate()
+
+        # Check that tx1 is the only transaction of the 3 in the template.
+        template_txids = [ t['txid'] for t in template['transactions'] ]
+        assert(txid2 not in template_txids and txid3 not in template_txids)
+        assert(txid1 in template_txids)
+
+        # Check that running with segwit support results in all 3 being included.
+        template = self.nodes[0].getblocktemplate({"rules": ["segwit"]})
+        template_txids = [ t['txid'] for t in template['transactions'] ]
+        assert(txid1 in template_txids)
+        assert(txid2 in template_txids)
+        assert(txid3 in template_txids)
+
+        # Mine a block to clear the gbt cache again.
+        self.nodes[0].generate(1)
 
         self.log.info("Verify behaviour of importaddress, addwitnessaddress and listunspent")