[wallet] fix zapwallettxes interaction with persistent mempool

zapwallettxes previously did not interact well with persistent mempool.
zapwallettxes would cause wallet transactions to be zapped, but they
would then be reloaded from the mempool on startup. This commit softsets
persistmempool to false if zapwallettxes is enabled so transactions are
actually zapped.

src/wallet/wallet.cpp

@@ -4043,6 +4043,11 @@ bool CWallet::ParameterInteraction()
         }
     }
 
+    // -zapwallettx implies dropping the mempool on startup
+    if (GetBoolArg("-zapwallettxes", false) && SoftSetBoolArg("-persistmempool", false)) {
+        LogPrintf("%s: parameter interaction: -zapwallettxes=<mode> -> setting -persistmempool=0\n", __func__);
+    }
+
     // -zapwallettx implies a rescan
     if (GetBoolArg("-zapwallettxes", false)) {
         if (is_multiwallet) {

test/functional/zapwallettxes.py

@@ -4,20 +4,19 @@
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 """Test the zapwallettxes functionality.
 
-- start three bitcoind nodes
-- create four transactions on node 0 - two are confirmed and two are
-  unconfirmed.
-- restart node 1 and verify that both the confirmed and the unconfirmed
+- start two bitcoind nodes
+- create two transactions on node 0 - one is confirmed and one is unconfirmed.
+- restart node 0 and verify that both the confirmed and the unconfirmed
   transactions are still available.
-- restart node 0 and verify that the confirmed transactions are still
-  available, but that the unconfirmed transaction has been zapped.
+- restart node 0 with zapwallettxes and persistmempool, and verify that both
+  the confirmed and the unconfirmed transactions are still available.
+- restart node 0 with just zapwallettxed and verify that the confirmed
+  transactions are still available, but that the unconfirmed transaction has
+  been zapped.
 """
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (assert_equal,
-                                 assert_raises,
-                                 bitcoind_processes,
-                                 connect_nodes_bi,
-                                 JSONRPCException,
+                                 assert_raises_jsonrpc,
                                  )
 
 class ZapWalletTXesTest (BitcoinTestFramework):
@@ -25,60 +24,53 @@ class ZapWalletTXesTest (BitcoinTestFramework):
     def __init__(self):
         super().__init__()
         self.setup_clean_chain = True
-        self.num_nodes = 3
-
-    def setup_network(self):
-        super().setup_network()
-        connect_nodes_bi(self.nodes, 0, 2)
+        self.num_nodes = 2
 
     def run_test(self):
         self.log.info("Mining blocks...")
         self.nodes[0].generate(1)
         self.sync_all()
-        self.nodes[1].generate(101)
+        self.nodes[1].generate(100)
         self.sync_all()
 
-        assert_equal(self.nodes[0].getbalance(), 50)
+        # This transaction will be confirmed
+        txid1 = self.nodes[0].sendtoaddress(self.nodes[1].getnewaddress(), 10)
 
-        txid0 = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), 11)
-        txid1 = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), 10)
-        self.sync_all()
         self.nodes[0].generate(1)
         self.sync_all()
 
-        txid2 = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), 11)
-        txid3 = self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), 10)
-
-        tx0 = self.nodes[0].gettransaction(txid0)
-        assert_equal(tx0['txid'], txid0)  # tx0 must be available (confirmed)
+        # This transaction will not be confirmed
+        txid2 = self.nodes[0].sendtoaddress(self.nodes[1].getnewaddress(), 20)
 
-        tx1 = self.nodes[0].gettransaction(txid1)
-        assert_equal(tx1['txid'], txid1)  # tx1 must be available (confirmed)
+        # Confirmed and unconfirmed transactions are now in the wallet.
+        assert_equal(self.nodes[0].gettransaction(txid1)['txid'], txid1)
+        assert_equal(self.nodes[0].gettransaction(txid2)['txid'], txid2)
 
-        tx2 = self.nodes[0].gettransaction(txid2)
-        assert_equal(tx2['txid'], txid2)  # tx2 must be available (unconfirmed)
-
-        tx3 = self.nodes[0].gettransaction(txid3)
-        assert_equal(tx3['txid'], txid3)  # tx3 must be available (unconfirmed)
-
-        #restart bitcoind
+        # Stop-start node0. Both confirmed and unconfirmed transactions remain in the wallet.
         self.stop_node(0)
         self.nodes[0] = self.start_node(0, self.options.tmpdir)
 
-        tx3 = self.nodes[0].gettransaction(txid3)
-        assert_equal(tx3['txid'], txid3)  # tx must be available (unconfirmed)
+        assert_equal(self.nodes[0].gettransaction(txid1)['txid'], txid1)
+        assert_equal(self.nodes[0].gettransaction(txid2)['txid'], txid2)
 
+        # Stop node0 and restart with zapwallettxes and persistmempool. The unconfirmed
+        # transaction is zapped from the wallet, but is re-added when the mempool is reloaded.
         self.stop_node(0)
+        self.nodes[0] = self.start_node(0, self.options.tmpdir, ["-persistmempool=1", "-zapwallettxes=2"])
 
-        #restart bitcoind with zapwallettxes
-        self.nodes[0] = self.start_node(0,self.options.tmpdir, ["-zapwallettxes=1"])
+        assert_equal(self.nodes[0].gettransaction(txid1)['txid'], txid1)
+        assert_equal(self.nodes[0].gettransaction(txid2)['txid'], txid2)
 
-        assert_raises(JSONRPCException, self.nodes[0].gettransaction, [txid3])
-        # there must be an exception because the unconfirmed wallettx0 must be gone by now
+        # Stop node0 and restart with zapwallettxes, but not persistmempool.
+        # The unconfirmed transaction is zapped and is no longer in the wallet.
+        self.stop_node(0)
+        self.nodes[0] = self.start_node(0, self.options.tmpdir, ["-zapwallettxes=2"])
 
-        tx0 = self.nodes[0].gettransaction(txid0)
-        assert_equal(tx0['txid'], txid0)  # tx0 (confirmed) must still be available because it was confirmed
+        # tx1 is still be available because it was confirmed
+        assert_equal(self.nodes[0].gettransaction(txid1)['txid'], txid1)
 
+        # This will raise an exception because the unconfirmed transaction has been zapped
+        assert_raises_jsonrpc(-5, 'Invalid or non-wallet transaction id', self.nodes[0].gettransaction, txid2)
 
 if __name__ == '__main__':
     ZapWalletTXesTest().main()