From f826e90ac3fb05b6f43f132542376acda88c393d Mon Sep 17 00:00:00 2001
From: Jon Atack <jon@atack.com>
Date: Sun, 15 Nov 2020 16:15:11 +0100
Subject: [PATCH 1/8] policy: add CFeeRate::SatsToString helper without units

---
 src/policy/feerate.cpp    | 4 ++++
 src/policy/feerate.h      | 3 +++
 src/test/amount_tests.cpp | 8 ++++++++
 3 files changed, 15 insertions(+)

diff --git a/src/policy/feerate.cpp b/src/policy/feerate.cpp
index eb0cba5c67..34795a84fc 100644
--- a/src/policy/feerate.cpp
+++ b/src/policy/feerate.cpp
@@ -43,3 +43,7 @@ std::string CFeeRate::ToString(const FeeEstimateMode& fee_estimate_mode) const
     default:                      return strprintf("%d.%08d %s/kvB", nSatoshisPerK / COIN, nSatoshisPerK % COIN, CURRENCY_UNIT);
     }
 }
+
+std::string CFeeRate::SatsToString() const {
+    return strprintf("%d.%03d", nSatoshisPerK / 1000, nSatoshisPerK % 1000);
+}
diff --git a/src/policy/feerate.h b/src/policy/feerate.h
index 41f4a4d06b..586d5df56f 100644
--- a/src/policy/feerate.h
+++ b/src/policy/feerate.h
@@ -70,7 +70,10 @@ public:
     friend bool operator>=(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK >= b.nSatoshisPerK; }
     friend bool operator!=(const CFeeRate& a, const CFeeRate& b) { return a.nSatoshisPerK != b.nSatoshisPerK; }
     CFeeRate& operator+=(const CFeeRate& a) { nSatoshisPerK += a.nSatoshisPerK; return *this; }
+    /** Return the fee rate in sat/vB or BTC/kvB, with units, as a string. */
     std::string ToString(const FeeEstimateMode& fee_estimate_mode = FeeEstimateMode::BTC_KVB) const;
+    /** Return the fee rate in sat/vB, without units, as a string. */
+    std::string SatsToString() const;
 
     SERIALIZE_METHODS(CFeeRate, obj) { READWRITE(obj.nSatoshisPerK); }
 };
diff --git a/src/test/amount_tests.cpp b/src/test/amount_tests.cpp
index 3815a5bba6..31832e9893 100644
--- a/src/test/amount_tests.cpp
+++ b/src/test/amount_tests.cpp
@@ -113,4 +113,12 @@ BOOST_AUTO_TEST_CASE(ToStringTest)
     BOOST_CHECK_EQUAL(feeRate.ToString(FeeEstimateMode::SAT_VB), "0.001 sat/vB");
 }
 
+BOOST_AUTO_TEST_CASE(SatsToStringTest)
+{
+    BOOST_CHECK_EQUAL(CFeeRate(1).SatsToString(), "0.001");
+    BOOST_CHECK_EQUAL(CFeeRate(70).SatsToString(), "0.070");
+    BOOST_CHECK_EQUAL(CFeeRate(3141).SatsToString(), "3.141");
+    BOOST_CHECK_EQUAL(CFeeRate(10002).SatsToString(), "10.002");
+}
+
 BOOST_AUTO_TEST_SUITE_END()

From ac3219aca3a10dd01db8bba17015f7c6a5c2c1f4 Mon Sep 17 00:00:00 2001
From: Luke Dashjr <luke-jr+git@utopios.org>
Date: Wed, 25 Nov 2020 01:09:17 +0000
Subject: [PATCH 2/8] core_io: Add ValueFromFeeRate helper

---
 src/core_io.h      | 2 ++
 src/core_write.cpp | 6 ++++++
 2 files changed, 8 insertions(+)

diff --git a/src/core_io.h b/src/core_io.h
index 1f5ecbaea6..c8349c7594 100644
--- a/src/core_io.h
+++ b/src/core_io.h
@@ -13,6 +13,7 @@
 
 class CBlock;
 class CBlockHeader;
+class CFeeRate;
 class CScript;
 class CTransaction;
 struct CMutableTransaction;
@@ -50,6 +51,7 @@ bool ParseHashStr(const std::string& strHex, uint256& result);
 
 // core_write.cpp
 UniValue ValueFromAmount(const CAmount amount);
+UniValue ValueFromFeeRate(const CFeeRate& fee_rate);
 std::string FormatScript(const CScript& script);
 std::string EncodeHexTx(const CTransaction& tx, const int serializeFlags = 0);
 std::string SighashToStr(unsigned char sighash_type);
diff --git a/src/core_write.cpp b/src/core_write.cpp
index 7cf019a42e..4f5a6703a1 100644
--- a/src/core_write.cpp
+++ b/src/core_write.cpp
@@ -9,6 +9,7 @@
 #include <consensus/consensus.h>
 #include <consensus/validation.h>
 #include <key_io.h>
+#include <policy/feerate.h>
 #include <script/descriptor.h>
 #include <script/script.h>
 #include <script/solver.h>
@@ -36,6 +37,11 @@ UniValue ValueFromAmount(const CAmount amount)
             strprintf("%s%d.%08d", amount < 0 ? "-" : "", quotient, remainder));
 }
 
+UniValue ValueFromFeeRate(const CFeeRate& fee_rate)
+{
+    return UniValue(UniValue::VNUM, fee_rate.SatsToString());
+}
+
 std::string FormatScript(const CScript& script)
 {
     std::string ret;

From ecadc716dd1392f27f2929649e3592d014c8bcc8 Mon Sep 17 00:00:00 2001
From: Jon Atack <jon@atack.com>
Date: Mon, 30 Nov 2020 11:18:00 +0100
Subject: [PATCH 3/8] test: add ValueFromFeeRate/CFeeRate unit tests

(partial: CFeeRate in 0.21 doesn't take FeeEstimateMode)
---
 src/test/rpc_tests.cpp | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/src/test/rpc_tests.cpp b/src/test/rpc_tests.cpp
index 0d2460c606..768cf4549a 100644
--- a/src/test/rpc_tests.cpp
+++ b/src/test/rpc_tests.cpp
@@ -308,6 +308,17 @@ BOOST_AUTO_TEST_CASE(rpc_parse_monetary_values)
     BOOST_CHECK_THROW(AmountFromValue(ValueFromString("93e+9")), UniValue); //overflow error
 }
 
+BOOST_AUTO_TEST_CASE(rpc_parse_fee_rate_values)
+{
+    // Test ValueFromFeeRate() and CFeeRate()
+    // ...using default CFeeRate constructor
+    BOOST_CHECK_EQUAL(ValueFromFeeRate(CFeeRate(AmountFromValue(0.00001234))).get_real(), 1.234);
+    BOOST_CHECK_EQUAL(ValueFromFeeRate(CFeeRate(AmountFromValue(0.1234))).get_real(), 12340.000);
+    BOOST_CHECK_EQUAL(ValueFromFeeRate(CFeeRate(AmountFromValue(1234))).get_real(), 123400000.000);
+    // ...using CFeeRate constructor with bytes 1000
+    BOOST_CHECK_EQUAL(ValueFromFeeRate(CFeeRate(AmountFromValue(0.00001234), 1000)).get_real(), 1.234);
+}
+
 BOOST_AUTO_TEST_CASE(rpc_ban)
 {
     BOOST_CHECK_NO_THROW(CallRPC(std::string("clearbanned")));

From 8173d2ae617c2390543d5e5ac252f6b5c578b686 Mon Sep 17 00:00:00 2001
From: Jon Atack <jon@atack.com>
Date: Sat, 14 Nov 2020 15:38:40 +0100
Subject: [PATCH 4/8] wallet: introduce setfeerate, an improved settxfee in
 sat/vB

Github-Pull: #20391
Rebased-From: 8e863e3d3ce457c9ca26a12e8fd6beac2f50aa7d (diff-minimised)
---
 src/rpc/client.cpp        |  1 +
 src/wallet/rpc/spend.cpp  | 74 +++++++++++++++++++++++++++++++++++++++
 src/wallet/rpc/wallet.cpp |  2 ++
 3 files changed, 77 insertions(+)

diff --git a/src/rpc/client.cpp b/src/rpc/client.cpp
index 49820f25a3..a181fd7d9d 100644
--- a/src/rpc/client.cpp
+++ b/src/rpc/client.cpp
@@ -47,6 +47,7 @@ static const CRPCConvertParam vRPCConvertParams[] =
     { "sendtoaddress", 8, "avoid_reuse" },
     { "sendtoaddress", 9, "fee_rate"},
     { "sendtoaddress", 10, "verbose"},
+    { "setfeerate", 0, "amount" },
     { "settxfee", 0, "amount" },
     { "sethdseed", 0, "newkeypool" },
     { "getreceivedbyaddress", 1, "minconf" },
diff --git a/src/wallet/rpc/spend.cpp b/src/wallet/rpc/spend.cpp
index 6b96fc4e49..b3ce7ac9ee 100644
--- a/src/wallet/rpc/spend.cpp
+++ b/src/wallet/rpc/spend.cpp
@@ -407,6 +407,80 @@ RPCHelpMan sendmany()
     };
 }
 
+RPCHelpMan setfeerate()
+{
+    return RPCHelpMan{
+        "setfeerate",
+        "\nSet the transaction fee rate in " + CURRENCY_ATOM + "/vB for this wallet.\n"
+        "Overrides the global -paytxfee configuration option. Like -paytxfee, it is not persisted after bitcoind shutdown/restart.\n"
+        "Can be deactivated by passing 0 as the fee rate, in which case automatic fee selection will be used by default.\n",
+        {
+            {"amount", RPCArg::Type::AMOUNT, RPCArg::Optional::NO, "The transaction fee rate in " + CURRENCY_ATOM + "/vB to set (0 to unset)"},
+        },
+        RPCResult{
+            RPCResult::Type::OBJ, "", "",
+            {
+                {RPCResult::Type::STR, "wallet_name", "Name of the wallet the fee rate setting applies to"},
+                {RPCResult::Type::NUM, "fee_rate", "Fee rate in " + CURRENCY_ATOM + "/vB for the wallet after this operation"},
+                {RPCResult::Type::STR, "result", /* optional */ true, "Description of result, if successful"},
+                {RPCResult::Type::STR, "error", /* optional */ true, "Description of error, if any"},
+            },
+        },
+        RPCExamples{
+            ""
+            "\nSet a fee rate of 1 " + CURRENCY_ATOM + "/vB\n"
+            + HelpExampleCli("setfeerate", "1") +
+            "\nSet a fee rate of 3.141 " + CURRENCY_ATOM + "/vB\n"
+            + HelpExampleCli("setfeerate", "3.141") +
+            "\nSet a fee rate of 7.75 " + CURRENCY_ATOM + "/vB with named arguments\n"
+            + HelpExampleCli("-named setfeerate", "amount=\"7.75\"") +
+            "\nSet a fee rate of 25 " + CURRENCY_ATOM + "/vB with the RPC\n"
+            + HelpExampleRpc("setfeerate", "25")
+        },
+        [&](const RPCHelpMan& self, const JSONRPCRequest& request) -> UniValue {
+            std::shared_ptr<CWallet> const rpc_wallet{GetWalletForJSONRPCRequest(request)};
+            if (!rpc_wallet) return NullUniValue;
+            CWallet& wallet = *rpc_wallet;
+
+            LOCK(wallet.cs_wallet);
+            const CFeeRate amount{AmountFromValue(request.params[0]), COIN /* sat/vB */};
+            const CFeeRate relay_min_feerate{wallet.chain().relayMinFee().GetFeePerK()};
+            const CFeeRate wallet_min_feerate{wallet.m_min_fee.GetFeePerK()};
+            const CFeeRate wallet_max_feerate{wallet.m_default_max_tx_fee, 1000 /* BTC/kvB */};
+            const CFeeRate zero{CFeeRate{0}};
+            const std::string amount_str{amount.ToString(FeeEstimateMode::SAT_VB)};
+            const std::string current_setting{strprintf("The current setting of %s for this wallet remains unchanged.", wallet.m_pay_tx_fee == zero ? "0 (unset)" : wallet.m_pay_tx_fee.ToString(FeeEstimateMode::SAT_VB))};
+            std::string result, error;
+
+            if (amount == zero) {
+                if (request.params[0].get_real() != 0) throw JSONRPCError(RPC_TYPE_ERROR, "Invalid amount");
+                wallet.m_pay_tx_fee = amount;
+                result = "Fee rate for transactions with this wallet successfully unset. By default, automatic fee selection will be used.";
+            } else if (amount < relay_min_feerate) {
+                error = strprintf("The requested fee rate of %s cannot be less than the minimum relay fee rate of %s. %s", amount_str, relay_min_feerate.ToString(FeeEstimateMode::SAT_VB), current_setting);
+            } else if (amount < wallet_min_feerate) {
+                error = strprintf("The requested fee rate of %s cannot be less than the wallet min fee rate of %s. %s", amount_str, wallet_min_feerate.ToString(FeeEstimateMode::SAT_VB), current_setting);
+            } else if (amount > wallet_max_feerate) {
+                error = strprintf("The requested fee rate of %s cannot be greater than the wallet max fee rate of %s. %s", amount_str, wallet_max_feerate.ToString(FeeEstimateMode::SAT_VB), current_setting);
+            } else {
+                wallet.m_pay_tx_fee = amount;
+                result = "Fee rate for transactions with this wallet successfully set to " + amount_str;
+            }
+            CHECK_NONFATAL(result.empty() != error.empty());
+
+            UniValue obj{UniValue::VOBJ};
+            obj.pushKV("wallet_name", wallet.GetName());
+            obj.pushKV("fee_rate", ValueFromFeeRate(wallet.m_pay_tx_fee));
+            if (error.empty()) {
+                obj.pushKV("result", result);
+            } else {
+                obj.pushKV("error", error);
+            }
+            return obj;
+        },
+    };
+}
+
 RPCHelpMan settxfee()
 {
     return RPCHelpMan{"settxfee",
diff --git a/src/wallet/rpc/wallet.cpp b/src/wallet/rpc/wallet.cpp
index 164ce9afed..3279f6ea13 100644
--- a/src/wallet/rpc/wallet.cpp
+++ b/src/wallet/rpc/wallet.cpp
@@ -858,6 +858,7 @@ RPCHelpMan encryptwallet();
 // spend
 RPCHelpMan sendtoaddress();
 RPCHelpMan sendmany();
+RPCHelpMan setfeerate();
 RPCHelpMan settxfee();
 RPCHelpMan fundrawtransaction();
 RPCHelpMan bumpfee();
@@ -937,6 +938,7 @@ Span<const CRPCCommand> GetWalletRPCCommands()
         {"wallet", &sendtoaddress},
         {"wallet", &sethdseed},
         {"wallet", &setlabel},
+        {"wallet", &setfeerate},
         {"wallet", &settxfee},
         {"wallet", &setwalletflag},
         {"wallet", &signmessage},

From b8b150a86505df10c2c55fbbba06d327f08f0938 Mon Sep 17 00:00:00 2001
From: Jon Atack <jon@atack.com>
Date: Fri, 27 Nov 2020 17:36:22 +0100
Subject: [PATCH 5/8] test: add setfeerate functional coverage in
 wallet_create_tx.py

Github-Pull: #20391
Rebased-From: 529bfc16ffb35c5356e27f61d59395fae6707bcd
---
 test/functional/wallet_create_tx.py | 51 ++++++++++++++++++++++++++++-
 1 file changed, 50 insertions(+), 1 deletion(-)

diff --git a/test/functional/wallet_create_tx.py b/test/functional/wallet_create_tx.py
index 4e31b48ec0..56fb926a84 100755
--- a/test/functional/wallet_create_tx.py
+++ b/test/functional/wallet_create_tx.py
@@ -3,6 +3,8 @@
 # Distributed under the MIT software license, see the accompanying
 # file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
+from decimal import Decimal
+
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
     assert_equal,
@@ -20,6 +22,7 @@ class CreateTxWalletTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 1
+        self.wallet_names = ["test_wallet"]
 
     def skip_test_if_missing_module(self):
         self.skip_if_no_wallet()
@@ -33,6 +36,7 @@ class CreateTxWalletTest(BitcoinTestFramework):
         self.test_anti_fee_sniping()
         self.test_tx_size_too_large()
         self.test_create_too_long_mempool_chain()
+        self.test_setfeerate()
 
     def test_anti_fee_sniping(self):
         self.log.info('Check that we have some (old) blocks and that anti-fee-sniping is disabled')
@@ -83,7 +87,7 @@ class CreateTxWalletTest(BitcoinTestFramework):
 
     def test_create_too_long_mempool_chain(self):
         self.log.info('Check too-long mempool chain error')
-        df_wallet = self.nodes[0].get_wallet_rpc(self.default_wallet_name)
+        df_wallet = self.nodes[0].get_wallet_rpc(self.wallet_names[0])
 
         self.nodes[0].createwallet("too_long")
         test_wallet = self.nodes[0].get_wallet_rpc("too_long")
@@ -106,6 +110,51 @@ class CreateTxWalletTest(BitcoinTestFramework):
 
         test_wallet.unloadwallet()
 
+    def test_setfeerate(self):
+        self.log.info("Test setfeerate")
+        self.restart_node(0, extra_args=["-mintxfee=0.00003141"])  # 3.141 sat/vB
+        node = self.nodes[0]
+
+        def test_response(*, requested=0, expected=0, error=None, msg):
+            assert_equal(node.setfeerate(requested), {"wallet_name": "test_wallet", "fee_rate": expected, ("error" if error else "result"): msg})
+
+        # Test setfeerate with 10.0001 (CFeeRate rounding), "10.001" and "4" sat/vB
+        test_response(requested=10.0001, expected=10, msg="Fee rate for transactions with this wallet successfully set to 10.000 sat/vB")
+        assert_equal(node.getwalletinfo()["paytxfee"], Decimal("0.00010000"))
+        test_response(requested="10.001", expected=Decimal("10.001"), msg="Fee rate for transactions with this wallet successfully set to 10.001 sat/vB")
+        assert_equal(node.getwalletinfo()["paytxfee"], Decimal("0.00010001"))
+        test_response(requested="4", expected=4, msg="Fee rate for transactions with this wallet successfully set to 4.000 sat/vB")
+        assert_equal(node.getwalletinfo()["paytxfee"], Decimal("0.00004000"))
+
+        # Test setfeerate with too-high/low values returns expected errors
+        test_response(requested=Decimal("10000.001"), expected=4, error=True, msg="The requested fee rate of 10000.001 sat/vB cannot be greater than the wallet max fee rate of 10000.000 sat/vB. The current setting of 4.000 sat/vB for this wallet remains unchanged.")
+        test_response(requested=Decimal("0.999"), expected=4, error=True, msg="The requested fee rate of 0.999 sat/vB cannot be less than the minimum relay fee rate of 1.000 sat/vB. The current setting of 4.000 sat/vB for this wallet remains unchanged.")
+        test_response(requested=Decimal("3.140"), expected=4, error=True, msg="The requested fee rate of 3.140 sat/vB cannot be less than the wallet min fee rate of 3.141 sat/vB. The current setting of 4.000 sat/vB for this wallet remains unchanged.")
+        assert_equal(node.getwalletinfo()["paytxfee"], Decimal("0.00004000"))
+
+        # Test setfeerate to 3.141 sat/vB
+        test_response(requested=3.141, expected=Decimal("3.141"), msg="Fee rate for transactions with this wallet successfully set to 3.141 sat/vB")
+        assert_equal(node.getwalletinfo()["paytxfee"], Decimal("0.00003141"))
+
+        # Test setfeerate with values non-representable by CFeeRate
+        for invalid_value in [0.00000001, 0.0009, 0.00099999]:
+            assert_raises_rpc_error(-3, "Invalid amount", node.setfeerate, amount=invalid_value)
+
+        # Test setfeerate with values rejected by ParseFixedPoint() called in AmountFromValue()
+        for invalid_value in ["", 0.000000001, "1.111111111", 11111111111]:
+            assert_raises_rpc_error(-3, "Invalid amount", node.setfeerate, amount=invalid_value)
+
+        # Test deactivating setfeerate
+        test_response(msg="Fee rate for transactions with this wallet successfully unset. By default, automatic fee selection will be used.")
+        assert_equal(node.getwalletinfo()["paytxfee"], 0)
+
+        # Test currently-unset setfeerate with too-high/low values returns expected errors
+        test_response(requested=Decimal("10000.001"), error=True, msg="The requested fee rate of 10000.001 sat/vB cannot be greater than the wallet max fee rate of 10000.000 sat/vB. The current setting of 0 (unset) for this wallet remains unchanged.")
+        assert_equal(node.getwalletinfo()["paytxfee"], 0)
+        test_response(requested=Decimal("0.999"), error=True, msg="The requested fee rate of 0.999 sat/vB cannot be less than the minimum relay fee rate of 1.000 sat/vB. The current setting of 0 (unset) for this wallet remains unchanged.")
+        test_response(requested=Decimal("3.140"), error=True, msg="The requested fee rate of 3.140 sat/vB cannot be less than the wallet min fee rate of 3.141 sat/vB. The current setting of 0 (unset) for this wallet remains unchanged.")
+        assert_equal(node.getwalletinfo()["paytxfee"], 0)
+
 
 if __name__ == '__main__':
     CreateTxWalletTest().main()

From 5030cae7c9e77c9edfb0de659aa41523a1faf50b Mon Sep 17 00:00:00 2001
From: Jon Atack <jon@atack.com>
Date: Fri, 27 Nov 2020 17:36:06 +0100
Subject: [PATCH 6/8] test: add setfeerate functional coverage in
 wallet_bumpfee.py

Github-Pull: #20391
Rebased-From: c907f158a6bf3cad782d4441e02abcbda210265b
---
 test/functional/wallet_bumpfee.py | 39 +++++++++++++++++++++++++++++++
 1 file changed, 39 insertions(+)

diff --git a/test/functional/wallet_bumpfee.py b/test/functional/wallet_bumpfee.py
index fea933a93b..4a093b350c 100755
--- a/test/functional/wallet_bumpfee.py
+++ b/test/functional/wallet_bumpfee.py
@@ -19,6 +19,7 @@ from test_framework.blocktools import (
     COINBASE_MATURITY,
 )
 from test_framework.messages import (
+    COIN,
     MAX_BIP125_RBF_SEQUENCE,
 )
 from test_framework.test_framework import BitcoinTestFramework
@@ -61,6 +62,7 @@ class BumpFeeTest(BitcoinTestFramework):
             "-addresstype=bech32",
             "-whitelist=noban@127.0.0.1",
         ] for i in range(self.num_nodes)]
+        self.wallet_names = [self.default_wallet_name, "RBF wallet"]
 
     def skip_test_if_missing_module(self):
         self.skip_if_no_wallet()
@@ -105,6 +107,7 @@ class BumpFeeTest(BitcoinTestFramework):
         test_bumpfee_metadata(self, rbf_node, dest_address)
         test_locked_wallet_fails(self, rbf_node, dest_address)
         test_change_script_match(self, rbf_node, dest_address)
+        test_setfeerate(self, rbf_node, dest_address)
         test_settxfee(self, rbf_node, dest_address)
         test_maxtxfee_fails(self, rbf_node, dest_address)
         # These tests wipe out a number of utxos that are expected in other tests
@@ -530,6 +533,42 @@ def test_dust_to_fee(self, rbf_node, dest_address):
     self.clear_mempool()
 
 
+def test_setfeerate(self, rbf_node, dest_address):
+    self.log.info("Test setfeerate")
+
+    def test_response(*, wallet="RBF wallet", requested=0, expected=0, error=None, msg):
+        assert_equal(rbf_node.setfeerate(requested), {"wallet_name": wallet, "fee_rate": expected, ("error" if error else "result"): msg})
+
+    # Test setfeerate with too high/low values returns expected errors
+    new = Decimal("10000.001")
+    test_response(requested=new, error=True, msg=f"The requested fee rate of {new} sat/vB cannot be greater than the wallet max fee rate of 10000.000 sat/vB. The current setting of 0 (unset) for this wallet remains unchanged.")
+    new = Decimal("0.999")
+    test_response(requested=new, error=True, msg=f"The requested fee rate of {new} sat/vB cannot be less than the minimum relay fee rate of 1.000 sat/vB. The current setting of 0 (unset) for this wallet remains unchanged.")
+    fee_rate = Decimal("2.001")
+    test_response(requested=fee_rate, expected=fee_rate, msg=f"Fee rate for transactions with this wallet successfully set to {fee_rate} sat/vB")
+    new = Decimal("1.999")
+    test_response(requested=new, expected=fee_rate, error=True, msg=f"The requested fee rate of {new} sat/vB cannot be less than the wallet min fee rate of 2.000 sat/vB. The current setting of {fee_rate} sat/vB for this wallet remains unchanged.")
+
+    # Test setfeerate with valid values returns expected results
+    rbfid = spend_one_input(rbf_node, dest_address)
+    fee_rate = 25
+    test_response(requested=fee_rate, expected=fee_rate, msg="Fee rate for transactions with this wallet successfully set to 25.000 sat/vB")
+    bumped_tx = rbf_node.bumpfee(rbfid)
+    actual_feerate = bumped_tx["fee"] * COIN / rbf_node.getrawtransaction(bumped_tx["txid"], True)["vsize"]
+    assert_greater_than(Decimal("0.01"), abs(fee_rate - actual_feerate))
+    test_response(msg="Fee rate for transactions with this wallet successfully unset. By default, automatic fee selection will be used.")
+
+    # Test setfeerate with a different -maxtxfee
+    self.restart_node(1, ["-maxtxfee=0.000025"] + self.extra_args[1])
+    new = "2.501"
+    test_response(requested=new, error=True, msg=f"The requested fee rate of {new} sat/vB cannot be greater than the wallet max fee rate of 2.500 sat/vB. The current setting of 0 (unset) for this wallet remains unchanged.")
+
+    self.restart_node(1, self.extra_args[1])
+    rbf_node.walletpassphrase(WALLET_PASSPHRASE, WALLET_PASSPHRASE_TIMEOUT)
+    self.connect_nodes(1, 0)
+    self.clear_mempool()
+
+
 def test_settxfee(self, rbf_node, dest_address):
     self.log.info('Test settxfee')
     assert_raises_rpc_error(-8, "txfee cannot be less than min relay tx fee", rbf_node.settxfee, Decimal('0.000005'))

From 309b6be8a1fb27dd2a669911e312e842211c4fff Mon Sep 17 00:00:00 2001
From: Jon Atack <jon@atack.com>
Date: Sat, 14 Nov 2020 19:44:59 +0100
Subject: [PATCH 7/8] test: add more functional tests for setfeerate

Was: test: update functional tests from settxfee to setfeerate

Github-Pull: #20391
Rebased-From: d87f0f3a923dca2ce8d99aa700b0beda8e42d3ec (partial)
---
 test/functional/wallet_create_tx.py   | 7 +++++++
 test/functional/wallet_multiwallet.py | 8 +++++++-
 2 files changed, 14 insertions(+), 1 deletion(-)

diff --git a/test/functional/wallet_create_tx.py b/test/functional/wallet_create_tx.py
index 56fb926a84..e7cbf03c11 100755
--- a/test/functional/wallet_create_tx.py
+++ b/test/functional/wallet_create_tx.py
@@ -55,6 +55,7 @@ class CreateTxWalletTest(BitcoinTestFramework):
         # More than 10kB of outputs, so that we hit -maxtxfee with a high feerate
         outputs = {self.nodes[0].getnewaddress(address_type='bech32'): 0.000025 for _ in range(400)}
         raw_tx = self.nodes[0].createrawtransaction(inputs=[], outputs=outputs)
+        msg = "Fee exceeds maximum configured by user (e.g. -maxtxfee, maxfeerate)"
 
         for fee_setting in ['-minrelaytxfee=0.01', '-mintxfee=0.01', '-paytxfee=0.01']:
             self.log.info('Check maxtxfee in combination with {}'.format(fee_setting))
@@ -85,6 +86,12 @@ class CreateTxWalletTest(BitcoinTestFramework):
         )
         self.nodes[0].settxfee(0)
 
+        self.log.info('Check maxtxfee in combination with setfeerate (sat/vB)')
+        self.nodes[0].setfeerate(1000)
+        assert_raises_rpc_error(-6, msg, self.nodes[0].sendmany, dummy="", amounts=outputs)
+        assert_raises_rpc_error(-4, msg, self.nodes[0].fundrawtransaction, hexstring=raw_tx)
+        self.nodes[0].setfeerate(0)
+
     def test_create_too_long_mempool_chain(self):
         self.log.info('Check too-long mempool chain error')
         df_wallet = self.nodes[0].get_wallet_rpc(self.wallet_names[0])
diff --git a/test/functional/wallet_multiwallet.py b/test/functional/wallet_multiwallet.py
index 10bc516d8f..acbb7f843c 100755
--- a/test/functional/wallet_multiwallet.py
+++ b/test/functional/wallet_multiwallet.py
@@ -250,12 +250,18 @@ class MultiWalletTest(BitcoinTestFramework):
         assert_equal(batch[0]["result"]["chain"], self.chain)
         assert_equal(batch[1]["result"]["walletname"], "w1")
 
-        self.log.info('Check for per-wallet settxfee call')
+        self.log.info('Test per-wallet setfeerate and settxfee calls')
         assert_equal(w1.getwalletinfo()['paytxfee'], 0)
         assert_equal(w2.getwalletinfo()['paytxfee'], 0)
+        w2.setfeerate(200)
+        assert_equal(w1.getwalletinfo()['paytxfee'], 0)
+        assert_equal(w2.getwalletinfo()['paytxfee'], Decimal('0.00200000'))
         w2.settxfee(0.001)
         assert_equal(w1.getwalletinfo()['paytxfee'], 0)
         assert_equal(w2.getwalletinfo()['paytxfee'], Decimal('0.00100000'))
+        w1.setfeerate(30)
+        assert_equal(w1.getwalletinfo()['paytxfee'], Decimal('0.00030000'))
+        assert_equal(w2.getwalletinfo()['paytxfee'], Decimal('0.00100000'))
 
         self.log.info("Test dynamic wallet loading")
 

From f9561082743cccbecd99eef1751302701dd631a6 Mon Sep 17 00:00:00 2001
From: Luke Dashjr <luke-jr+git@utopios.org>
Date: Wed, 30 Jun 2021 01:31:21 +0000
Subject: [PATCH 8/8] Bugfix: QA: When testing setfeerate, check approximate
 fee range with a span able to tolerate normal signature length variation

---
 test/functional/wallet_bumpfee.py | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/test/functional/wallet_bumpfee.py b/test/functional/wallet_bumpfee.py
index 4a093b350c..213864a0b9 100755
--- a/test/functional/wallet_bumpfee.py
+++ b/test/functional/wallet_bumpfee.py
@@ -24,6 +24,7 @@ from test_framework.messages import (
 )
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import (
+    assert_approx,
     assert_equal,
     assert_fee_amount,
     assert_greater_than,
@@ -554,8 +555,10 @@ def test_setfeerate(self, rbf_node, dest_address):
     fee_rate = 25
     test_response(requested=fee_rate, expected=fee_rate, msg="Fee rate for transactions with this wallet successfully set to 25.000 sat/vB")
     bumped_tx = rbf_node.bumpfee(rbfid)
-    actual_feerate = bumped_tx["fee"] * COIN / rbf_node.getrawtransaction(bumped_tx["txid"], True)["vsize"]
-    assert_greater_than(Decimal("0.01"), abs(fee_rate - actual_feerate))
+    bumped_txdetails = rbf_node.getrawtransaction(bumped_tx["txid"], True)
+    allow_for_bytes_offset = len(bumped_txdetails['vout']) * 2  # potentially up to 2 bytes per output
+    actual_fee = bumped_tx["fee"] * COIN
+    assert_approx(actual_fee, fee_rate * bumped_txdetails['vsize'], fee_rate * allow_for_bytes_offset)
     test_response(msg="Fee rate for transactions with this wallet successfully unset. By default, automatic fee selection will be used.")
 
     # Test setfeerate with a different -maxtxfee