Merge #17219: wallet: allow transaction without change if keypool is empty

92bcd70808b9cac56b184903aa6d37baf9641b37 [wallet] allow transaction without change if keypool is empty (Sjors Provoost)
709f8685ac37510aa145ac259753583c82280038 [wallet] CreateTransaction: simplify change address check (Sjors Provoost)
5efc25f9638866941028454cfa9bae27f1519cb4 [wallet] translate "Keypool ran out" message (Sjors Provoost)

Pull request description:

  Extracted from #16944

  First this PR simplifies the check when generating a change address, by dropping `CanGetAddresses` and just letting `reservedest.GetReservedDestination` do this check.

  Second, when the keypool is empty, instead of immediately giving up, we create a dummy change address and pass that to coin selection. If we didn't need the change address (e.g. when spending the entire balance), then it's all good. If we did need a change address, we throw the original error.

ACKs for top commit:
  fjahr:
    Code review ACK 92bcd70808b9cac56b184903aa6d37baf9641b37
  jonasschnelli:
    utACK 92bcd70808b9cac56b184903aa6d37baf9641b37
  achow101:
    ACK 92bcd70808b9cac56b184903aa6d37baf9641b37
  meshcollider:
    Code review ACK 92bcd70808b9cac56b184903aa6d37baf9641b37

Tree-SHA512: 07b8c8251f57061c58a85ebf0359be63583c23bac7a2c4cefdc14820c0cdebcc90a2bb218e5ede0db11d1e204cda149e056dfd18614642070b3d56efe2735006

1 files changed, 7 insertions, 2 deletions

diff --git a/test/functional/rpc_fundrawtransaction.py b/test/functional/rpc_fundrawtransaction.py
index 891c4393b3..4bc4913bda 100755
--- a/test/functional/rpc_fundrawtransaction.py
+++ b/test/functional/rpc_fundrawtransaction.py
@@ -500,11 +500,16 @@ class RawTransactionsTest(BitcoinTestFramework):
         self.nodes[1].getnewaddress()
         self.nodes[1].getrawchangeaddress()
         inputs = []
-        outputs = {self.nodes[0].getnewaddress():1.1}
+        outputs = {self.nodes[0].getnewaddress():1.09999500}
         rawtx = self.nodes[1].createrawtransaction(inputs, outputs)
+        # fund a transaction that does not require a new key for the change output
+        self.nodes[1].fundrawtransaction(rawtx)
+
         # fund a transaction that requires a new key for the change output
         # creating the key must be impossible because the wallet is locked
-        assert_raises_rpc_error(-4, "Keypool ran out, please call keypoolrefill first", self.nodes[1].fundrawtransaction, rawtx)
+        outputs = {self.nodes[0].getnewaddress():1.1}
+        rawtx = self.nodes[1].createrawtransaction(inputs, outputs)
+        assert_raises_rpc_error(-4, "Transaction needs a change address, but we can't generate it. Please call keypoolrefill first.", self.nodes[1].fundrawtransaction, rawtx)
 
         # Refill the keypool.
         self.nodes[1].walletpassphrase("test", 100)