Merge #257: Add joinpsbt command

b1e329c add joinpsbt (thesimplekid)

Pull request description:

ACKs for top commit:
  apoelstra:
    ACK b1e329c

Tree-SHA512: ada2e72d9decf1a7acf6a6139bfaef9109474baf8d6e90c572cdd66e3eebd9d76261f3134f71d1ba8fed80a81acae8435657fc363e5df655038b163ad8186466

Author: apoelstra

client/src/client.rs

@@ -1103,6 +1103,10 @@ pub trait RpcApi: Sized {
         self.call("getdescriptorinfo", &[desc.to_string().into()])
     }
 
+    fn join_psbt(&self, psbts: &[String]) -> Result<String> {
+        self.call("joinpsbts", &[into_json(psbts)?])
+    }
+
     fn combine_psbt(&self, psbts: &[String]) -> Result<String> {
         self.call("combinepsbt", &[into_json(psbts)?])
     }

integration_test/src/main.rs

@@ -25,8 +25,8 @@ use bitcoin::hashes::hex::{FromHex, ToHex};
 use bitcoin::hashes::Hash;
 use bitcoin::secp256k1;
 use bitcoin::{
-    Address, Amount, PackedLockTime, Network, OutPoint, PrivateKey, Script, EcdsaSighashType, SignedAmount,
-    Sequence, Transaction, TxIn, TxOut, Txid, Witness,
+    Address, Amount, EcdsaSighashType, Network, OutPoint, PackedLockTime, PrivateKey, Script,
+    Sequence, SignedAmount, Transaction, TxIn, TxOut, Txid, Witness,
 };
 use bitcoincore_rpc::bitcoincore_rpc_json::{
     GetBlockTemplateModes, GetBlockTemplateRules, ScanTxOutRequest,
@@ -172,6 +172,7 @@ fn main() {
     test_test_mempool_accept(&cl);
     test_wallet_create_funded_psbt(&cl);
     test_wallet_process_psbt(&cl);
+    test_join_psbt(&cl);
     test_combine_psbt(&cl);
     test_finalize_psbt(&cl);
     test_list_received_by_address(&cl);
@@ -782,6 +783,40 @@ fn test_wallet_process_psbt(cl: &Client) {
     assert!(res.complete);
 }
 
+fn test_join_psbt(cl: &Client) {
+    let options = json::ListUnspentQueryOptions {
+        minimum_amount: Some(btc(2)),
+        ..Default::default()
+    };
+    let unspent = cl.list_unspent(Some(6), None, None, None, Some(options)).unwrap();
+    let unspent1 = unspent[0].clone();
+    let input = json::CreateRawTransactionInput {
+        txid: unspent1.txid,
+        vout: unspent1.vout,
+        sequence: None,
+    };
+    let mut output = HashMap::new();
+    output.insert(RANDOM_ADDRESS.to_string(), btc(1));
+    let psbt1 = cl
+        .wallet_create_funded_psbt(&[input.clone()], &output, Some(500_000), None, Some(true))
+        .unwrap();
+
+    let unspent = unspent.into_iter().nth(1).unwrap();
+    let input2 = json::CreateRawTransactionInput {
+        txid: unspent.txid,
+        vout: unspent.vout,
+        sequence: None,
+    };
+    let mut output2 = HashMap::new();
+    output2.insert(RANDOM_ADDRESS.to_string(), btc(1));
+    let psbt2 = cl
+        .wallet_create_funded_psbt(&[input2.clone()], &output, Some(500_000), None, Some(true))
+        .unwrap();
+
+    let psbt = cl.join_psbt(&[psbt1.psbt, psbt2.psbt]).unwrap();
+    assert!(!psbt.is_empty());
+}
+
 fn test_combine_psbt(cl: &Client) {
     let options = json::ListUnspentQueryOptions {
         minimum_amount: Some(btc(2)),