wallet, rpc: deprecate settxfee and paytxfee

test/functional/wallet_create_tx.py

@@ -23,6 +23,7 @@ class CreateTxWalletTest(BitcoinTestFramework):
     def set_test_params(self):
         self.setup_clean_chain = True
         self.num_nodes = 1
+        self.extra_args = [["-deprecatedrpc=settxfee"]]
 
     def skip_test_if_missing_module(self):
         self.skip_if_no_wallet()
@@ -71,7 +72,7 @@ class CreateTxWalletTest(BitcoinTestFramework):
             )
 
         self.log.info('Check maxtxfee in combination with settxfee')
-        self.restart_node(0)
+        self.restart_node(0, expected_stderr='Warning: -paytxfee is deprecated and will be fully removed in v31.0.')
         self.nodes[0].settxfee(0.01)
         assert_raises_rpc_error(
             -6,