Allow zero-fee fundrawtxn and walletcreatefundedpsbt calls

A check to raise an error on zero-fee txns was mistakenly extended in commit
a0d4957 from the bumpfee and send{toaddress, many} RPCs to also include
fundrawtransaction and walletcreatefundedpsbt.

This commit overrides zero fee rate checking for these two RPCs, not only for
the feeRate (BTC/kvB) arg to return to previous behavior, but also for the new
fee_rate (sat/vB) arg.

Github-Pull: #20426
Rebased-From: 1b3d7009280595108eb22ac1188bc43678

1 files changed, 8 insertions, 7 deletions

diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
index 498197b5e5..5840801b00 100755
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -192,26 +192,27 @@ class PSBTTest(BitcoinTestFramework):
         assert_approx(res1["fee"], 0.055, 0.005)
         res2 = self.nodes[1].walletcreatefundedpsbt(inputs, outputs, 0, {"feeRate": 0.1, "add_inputs": True})
         assert_approx(res2["fee"], 0.055, 0.005)
+
         self.log.info("Test min fee rate checks with walletcreatefundedpsbt are bypassed, e.g. a fee_rate under 1 sat/vB is allowed")
         res3 = self.nodes[1].walletcreatefundedpsbt(inputs, outputs, 0, {"fee_rate": 0.99999999, "add_inputs": True})
         assert_approx(res3["fee"], 0.00000381, 0.0000001)
         res4 = self.nodes[1].walletcreatefundedpsbt(inputs, outputs, 0, {"feeRate": 0.00000999, "add_inputs": True})
         assert_approx(res4["fee"], 0.00000381, 0.0000001)
 
+        self.log.info("Test min fee rate checks with walletcreatefundedpsbt are bypassed and that funding non-standard 'zero-fee' transactions is valid")
+        for param in ["fee_rate", "feeRate"]:
+            assert_equal(self.nodes[1].walletcreatefundedpsbt(inputs, outputs, 0, {param: 0, "add_inputs": True})["fee"], 0)
+
         self.log.info("Test invalid fee rate settings")
-        assert_raises_rpc_error(-8, "Invalid fee_rate 0.000 sat/vB (must be greater than 0)",
-            self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {"fee_rate": 0, "add_inputs": True})
-        assert_raises_rpc_error(-8, "Invalid feeRate 0.00000000 BTC/kvB (must be greater than 0)",
-            self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {"feeRate": 0, "add_inputs": True})
         for param, value in {("fee_rate", 100000), ("feeRate", 1)}:
             assert_raises_rpc_error(-4, "Fee exceeds maximum configured by user (e.g. -maxtxfee, maxfeerate)",
                 self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {param: value, "add_inputs": True})
             assert_raises_rpc_error(-3, "Amount out of range",
-                self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {"fee_rate": -1, "add_inputs": True})
+                self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {param: -1, "add_inputs": True})
             assert_raises_rpc_error(-3, "Amount is not a number or string",
-                self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {"fee_rate": {"foo": "bar"}, "add_inputs": True})
+                self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {param: {"foo": "bar"}, "add_inputs": True})
             assert_raises_rpc_error(-3, "Invalid amount",
-                self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {"fee_rate": "", "add_inputs": True})
+                self.nodes[1].walletcreatefundedpsbt, inputs, outputs, 0, {param: "", "add_inputs": True})
 
         self.log.info("- raises RPC error if both feeRate and fee_rate are passed")
         assert_raises_rpc_error(-8, "Cannot specify both fee_rate (sat/vB) and feeRate (BTC/kvB)",