Merge pull request #2446 from patricklodder/1.14.4-mintxfee-tests

Implements, tests and assures wallet operator ease-of-sovereignty and making 
sure that user-defined fee logic persists through versions in the future by 
fixing and testing -paytxfee

1. There was an override of ANY user-defined value to CWallet::GetMinimumFee

  - Former logic: always override any value with either -mintxfee or 
    -mintxrelayfee, whichever is highest
    
  - Proposed logic in this pull request:
    - if the user specifies a value, only override when it is lower than 
      -mintxfee or -mintxrelayfee - this works because we set any default
      -mintxfee to be the same as -paytxfee, unless the user explicitly 
      sets a -mintxfee.
    - if no value has been specified, use the rate from -mintxfee or 
      -mintxrelayfee, whichever is highest
      
2. Test that the interaction between the wallet parameters -paytxfee and 
   -mintxfee function as intended. This has to be done using rpc tests rather 
   than unit tests because it tests the actual parameters passed to the 
   executables.
   
3. Undoing the override exposed a misconfiguration in the bumpfee.py test, 
   where fees were explicitly set higher, yet ignored in subsequent bumps.

2 files changed, 86 insertions, 3 deletions

diff --git a/qa/rpc-tests/bumpfee.py b/qa/rpc-tests/bumpfee.py
index b23761b06..20a683922 100755
--- a/qa/rpc-tests/bumpfee.py
+++ b/qa/rpc-tests/bumpfee.py
@@ -210,9 +210,10 @@ def test_rebumping(rbf_node, dest_address):
     # check that re-bumping the original tx fails, but bumping the bumper succeeds
     rbf_node.settxfee(Decimal("10.00000000"))
     rbfid = create_fund_sign_send(rbf_node, {dest_address: 7.00000000})
-    bumped = rbf_node.bumpfee(rbfid, {"totalFee": 150000000})
-    assert_raises_jsonrpc(-4, "already bumped", rbf_node.bumpfee, rbfid, {"totalFee": 2000})
-    rbf_node.bumpfee(bumped["txid"], {"totalFee": 200000000})
+    bumped = rbf_node.bumpfee(rbfid, {"totalFee": 1050000000})
+    assert_raises_jsonrpc(-4, "already bumped", rbf_node.bumpfee, rbfid, {"totalFee": 11000})
+    rbf_node.bumpfee(bumped["txid"], {"totalFee": 1100000000})
+    rbf_node.settxfee(Decimal("0.00000000"))
 
 
 def test_rebumping_not_replaceable(rbf_node, dest_address):
diff --git a/qa/rpc-tests/paytxfee.py b/qa/rpc-tests/paytxfee.py
new file mode 100644
index 000000000..feec0c45c
--- /dev/null
+++ b/qa/rpc-tests/paytxfee.py
@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+# Copyright (c) 2021 The Dogecoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+"""PayTxFee QA test.
+
+# Tests wallet behavior of -paytxfee in relation to -mintxfee
+"""
+
+from test_framework.test_framework import BitcoinTestFramework
+from test_framework.util import *
+from decimal import Decimal
+
+class PayTxFeeTest(BitcoinTestFramework):
+
+    def __init__(self):
+        super().__init__()
+        self.setup_clean_chain = True
+        self.num_nodes = 4
+
+    def setup_nodes(self, split=False):
+        nodes = []
+
+        # node 0 has txindex to track txs
+        nodes.append(start_node(0, self.options.tmpdir,
+            ["-debug", '-txindex']))
+
+        # node 1 pays 0.1 DOGE on all txs due to implicit mintxfee = paytxfee
+        nodes.append(start_node(1, self.options.tmpdir,
+            ["-paytxfee=0.1", "-debug"]))
+
+        # node 2 will always pay 1 DOGE on all txs because of explicit mintxfee
+        nodes.append(start_node(2, self.options.tmpdir,
+            ["-mintxfee=1", "-paytxfee=0.1", "-debug"]))
+
+        # node 3 will always pay 0.1 DOGE on all txs despite explicit mintxfee of 0.01
+        nodes.append(start_node(3, self.options.tmpdir,
+            ["-mintxfee=0.01", "-paytxfee=0.1", "-debug"]))
+
+        return nodes
+
+    def run_test(self):
+
+        seed = 1000 # the amount to seed wallets with
+        amount = 995 # the amount to send back
+        targetAddress = self.nodes[0].getnewaddress()
+
+        # mine some blocks and prepare some coins
+        self.nodes[0].generate(102)
+        self.nodes[0].sendtoaddress(self.nodes[1].getnewaddress(), seed)
+        self.nodes[0].sendtoaddress(self.nodes[2].getnewaddress(), seed)
+        self.nodes[0].sendtoaddress(self.nodes[3].getnewaddress(), seed)
+        self.nodes[0].generate(1)
+        self.sync_all()
+
+        # create transactions
+        txid1 = self.nodes[1].sendtoaddress(targetAddress, amount)
+        txid2 = self.nodes[2].sendtoaddress(targetAddress, amount)
+        txid3 = self.nodes[3].sendtoaddress(targetAddress, amount)
+        self.sync_all()
+
+        # make sure correct fees were paid
+        tx1 = self.nodes[0].getrawtransaction(txid1, True)
+        tx2 = self.nodes[0].getrawtransaction(txid2, True)
+        tx3 = self.nodes[0].getrawtransaction(txid3, True)
+
+        assert_equal(tx1['vout'][0]['value'] + tx1['vout'][1]['value'], Decimal("999.9"))
+        assert_equal(tx2['vout'][0]['value'] + tx2['vout'][1]['value'], Decimal("999"))
+        assert_equal(tx3['vout'][0]['value'] + tx3['vout'][1]['value'], Decimal("999.9"))
+
+        # mine a block
+        self.nodes[0].generate(1);
+        self.sync_all()
+
+        # make sure all fees were mined
+        block = self.nodes[0].getblock(self.nodes[0].getbestblockhash())
+        coinbaseTx = self.nodes[0].getrawtransaction(block['tx'][0], True)
+
+        assert_equal(coinbaseTx['vout'][0]['value'], Decimal("500001.2"))
+
+if __name__ == '__main__':
+    PayTxFeeTest().main()