[wallet] allow transaction without change if keypool is empty

1 files changed, 54 insertions, 6 deletions

diff --git a/test/functional/wallet_keypool.py b/test/functional/wallet_keypool.py
index e3aeb61197..9e2f00e62f 100755
--- a/test/functional/wallet_keypool.py
+++ b/test/functional/wallet_keypool.py
@@ -5,6 +5,7 @@
 """Test the wallet keypool and interaction with wallet encryption/locking."""
 
 import time
+from decimal import Decimal
 
 from test_framework.test_framework import BitcoinTestFramework
 from test_framework.util import assert_equal, assert_raises_rpc_error
@@ -53,12 +54,12 @@ class KeyPoolTest(BitcoinTestFramework):
         assert_raises_rpc_error(-12, "Keypool ran out", nodes[0].getrawchangeaddress)
 
         # drain the external keys
-        addr.add(nodes[0].getnewaddress())
-        addr.add(nodes[0].getnewaddress())
-        addr.add(nodes[0].getnewaddress())
-        addr.add(nodes[0].getnewaddress())
-        addr.add(nodes[0].getnewaddress())
-        addr.add(nodes[0].getnewaddress())
+        addr.add(nodes[0].getnewaddress(address_type="bech32"))
+        addr.add(nodes[0].getnewaddress(address_type="bech32"))
+        addr.add(nodes[0].getnewaddress(address_type="bech32"))
+        addr.add(nodes[0].getnewaddress(address_type="bech32"))
+        addr.add(nodes[0].getnewaddress(address_type="bech32"))
+        addr.add(nodes[0].getnewaddress(address_type="bech32"))
         assert len(addr) == 6
         # the next one should fail
         assert_raises_rpc_error(-12, "Error: Keypool ran out, please call keypoolrefill first", nodes[0].getnewaddress)
@@ -82,5 +83,52 @@ class KeyPoolTest(BitcoinTestFramework):
         assert_equal(wi['keypoolsize_hd_internal'], 100)
         assert_equal(wi['keypoolsize'], 100)
 
+        # create a blank wallet
+        nodes[0].createwallet(wallet_name='w2', blank=True)
+        w2 = nodes[0].get_wallet_rpc('w2')
+
+        # refer to initial wallet as w1
+        w1 = nodes[0].get_wallet_rpc('')
+
+        # import private key and fund it
+        address = addr.pop()
+        privkey = w1.dumpprivkey(address)
+        res = w2.importmulti([{'scriptPubKey': {'address': address}, 'keys': [privkey], 'timestamp': 'now'}])
+        assert_equal(res[0]['success'], True)
+        w1.walletpassphrase('test', 100)
+
+        res = w1.sendtoaddress(address=address, amount=0.00010000)
+        nodes[0].generate(1)
+        destination = addr.pop()
+
+        # Using a fee rate (10 sat / byte) well above the minimum relay rate
+        # creating a 5,000 sat transaction with change should not be possible
+        assert_raises_rpc_error(-4, "Transaction needs a change address, but we can't generate it. Please call keypoolrefill first.", w2.walletcreatefundedpsbt, inputs=[], outputs=[{addr.pop(): 0.00005000}], options={"subtractFeeFromOutputs": [0], "feeRate": 0.00010})
+
+        # creating a 10,000 sat transaction without change, with a manual input, should still be possible
+        res = w2.walletcreatefundedpsbt(inputs=w2.listunspent(), outputs=[{destination: 0.00010000}], options={"subtractFeeFromOutputs": [0], "feeRate": 0.00010})
+        assert_equal("psbt" in res, True)
+
+        # creating a 10,000 sat transaction without change should still be possible
+        res = w2.walletcreatefundedpsbt(inputs=[], outputs=[{destination: 0.00010000}], options={"subtractFeeFromOutputs": [0], "feeRate": 0.00010})
+        assert_equal("psbt" in res, True)
+        # should work without subtractFeeFromOutputs if the exact fee is subtracted from the amount
+        res = w2.walletcreatefundedpsbt(inputs=[], outputs=[{destination: 0.00008900}], options={"feeRate": 0.00010})
+        assert_equal("psbt" in res, True)
+
+        # dust change should be removed
+        res = w2.walletcreatefundedpsbt(inputs=[], outputs=[{destination: 0.00008800}], options={"feeRate": 0.00010})
+        assert_equal("psbt" in res, True)
+
+        # create a transaction without change at the maximum fee rate, such that the output is still spendable:
+        res = w2.walletcreatefundedpsbt(inputs=[], outputs=[{destination: 0.00010000}], options={"subtractFeeFromOutputs": [0], "feeRate": 0.0008824})
+        assert_equal("psbt" in res, True)
+        assert_equal(res["fee"], Decimal("0.00009706"))
+
+        # creating a 10,000 sat transaction with a manual change address should be possible
+        res = w2.walletcreatefundedpsbt(inputs=[], outputs=[{destination: 0.00010000}], options={"subtractFeeFromOutputs": [0], "feeRate": 0.00010, "changeAddress": addr.pop()})
+        assert_equal("psbt" in res, True)
+
+
 if __name__ == '__main__':
     KeyPoolTest().main()