From 2c96ef57bd606524223da037375ef351ea69e949 Mon Sep 17 00:00:00 2001
From: jp1ac4 <121959000+jp1ac4@users.noreply.github.com>
Date: Mon, 11 Mar 2024 16:55:56 +0000
Subject: [PATCH] commands: exclude immature coins from coin selection

An immature coin could in principle be marked as change
as this depends only on whether the address is derived from
the wallet's change descriptor.
---
 src/commands/mod.rs | 42 +++++++++++++++++++++++++++++++++++++++---
 1 file changed, 39 insertions(+), 3 deletions(-)

diff --git a/src/commands/mod.rs b/src/commands/mod.rs
index 6cb372d7..80c9f8bd 100644
--- a/src/commands/mod.rs
+++ b/src/commands/mod.rs
@@ -470,7 +470,7 @@ impl DaemonControl {
                 .filter_map(|(op, c)| {
                     if c.block_info.is_some() {
                         Some((c, None)) // confirmed coins have no ancestor info
-                    } else if c.is_change {
+                    } else if c.is_change && !c.is_immature {
                         // In case the mempool_entry is None, the coin will be included without
                         // any ancestor info.
                         Some((
@@ -1691,7 +1691,7 @@ mod tests {
             txid: dummy_op.txid,
             vout: dummy_op.vout + 100,
         };
-        db_conn.new_unspent_coins(&[Coin {
+        let unconfirmed_coin = Coin {
             outpoint: confirmed_op_1,
             is_immature: false,
             block_info: None,
@@ -1700,7 +1700,8 @@ mod tests {
             is_change: true,
             spend_txid: None,
             spend_block: None,
-        }]);
+        };
+        db_conn.new_unspent_coins(&[unconfirmed_coin]);
         // Coin selection error due to insufficient funds.
         assert!(matches!(
             control.create_spend(&destinations, &[], 1, None),
@@ -1782,6 +1783,41 @@ mod tests {
         manual_input.sort();
         assert_eq!(auto_input, manual_input);
 
+        // Now check that the spend created above using auto-selection only works when the unconfirmed coin
+        // is change and not immature.
+        // 1. not change and not immature
+        db_conn.remove_coins(&[unconfirmed_coin.outpoint]);
+        let mut unconfirmed_coin_2 = unconfirmed_coin;
+        unconfirmed_coin_2.is_change = false;
+        unconfirmed_coin_2.is_immature = false; // (this is already the case)
+        db_conn.new_unspent_coins(&[unconfirmed_coin_2]);
+        assert!(matches!(
+            control.create_spend(&destinations, &[], 1, None),
+            Ok(CreateSpendResult::InsufficientFunds { .. }),
+        ));
+        // 2. change and immature
+        db_conn.remove_coins(&[unconfirmed_coin_2.outpoint]);
+        unconfirmed_coin_2.is_change = true;
+        unconfirmed_coin_2.is_immature = true;
+        db_conn.new_unspent_coins(&[unconfirmed_coin_2]);
+        assert!(matches!(
+            control.create_spend(&destinations, &[], 1, None),
+            Ok(CreateSpendResult::InsufficientFunds { .. }),
+        ));
+        // 3. not change and immature
+        db_conn.remove_coins(&[unconfirmed_coin_2.outpoint]);
+        unconfirmed_coin_2.is_change = false;
+        unconfirmed_coin_2.is_immature = true;
+        db_conn.new_unspent_coins(&[unconfirmed_coin_2]);
+        assert!(matches!(
+            control.create_spend(&destinations, &[], 1, None),
+            Ok(CreateSpendResult::InsufficientFunds { .. }),
+        ));
+
+        // Re-insert the original unconfirmed coin again.
+        db_conn.remove_coins(&[unconfirmed_coin_2.outpoint]);
+        db_conn.new_unspent_coins(&[unconfirmed_coin]);
+
         // Now do the same again, but this time specifying the change address to be the same
         // as for the auto spend.
         let change_address = bitcoin::Address::from_script(