Implement joinpsbts RPC and tests

Adds a joinpsbts RPC which combines multiple distinct PSBTs into
one PSBT.

1 files changed, 17 insertions, 0 deletions

diff --git a/test/functional/rpc_psbt.py b/test/functional/rpc_psbt.py
index 28507267ce..f1538b34a8 100755
--- a/test/functional/rpc_psbt.py
+++ b/test/functional/rpc_psbt.py
@@ -321,6 +321,23 @@ class PSBTTest(BitcoinTestFramework):
         assert "witness_utxo" not in decoded['inputs'][1] and "non_witness_utxo" not in decoded['inputs'][1]
         assert "witness_utxo" not in decoded['inputs'][2] and "non_witness_utxo" not in decoded['inputs'][2]
 
+        # Two PSBTs with a common input should not be joinable
+        psbt1 = self.nodes[1].createpsbt([{"txid":txid1, "vout":vout1}], {self.nodes[0].getnewaddress():Decimal('10.999')})
+        assert_raises_rpc_error(-8, "exists in multiple PSBTs", self.nodes[1].joinpsbts, [psbt1, updated])
+
+        # Join two distinct PSBTs
+        addr4 = self.nodes[1].getnewaddress("", "p2sh-segwit")
+        txid4 = self.nodes[0].sendtoaddress(addr4, 5)
+        vout4 = find_output(self.nodes[0], txid4, 5)
+        self.nodes[0].generate(6)
+        self.sync_all()
+        psbt2 = self.nodes[1].createpsbt([{"txid":txid4, "vout":vout4}], {self.nodes[0].getnewaddress():Decimal('4.999')})
+        psbt2 = self.nodes[1].walletprocesspsbt(psbt2)['psbt']
+        psbt2_decoded = self.nodes[0].decodepsbt(psbt2)
+        assert "final_scriptwitness" in psbt2_decoded['inputs'][0] and "final_scriptSig" in psbt2_decoded['inputs'][0]
+        joined = self.nodes[0].joinpsbts([psbt, psbt2])
+        joined_decoded = self.nodes[0].decodepsbt(joined)
+        assert len(joined_decoded['inputs']) == 4 and len(joined_decoded['outputs']) == 2 and "final_scriptwitness" not in joined_decoded['inputs'][3] and "final_scriptSig" not in joined_decoded['inputs'][3]
 
 
 if __name__ == '__main__':