tests(api): add coin selection to create_spend tests

src/commands/mod.rs

@@ -1083,6 +1083,12 @@ mod tests {
             spend_txid: None,
             spend_block: None,
         }]);
+        // If we try to use coin selection, the unconfirmed coin will not be used as a candidate
+        // and so we get a coin selection error due to insufficient funds.
+        assert!(matches!(
+            control.create_spend(&destinations, &[], 1),
+            Err(CommandError::CoinSelectionError(..))
+        ));
         let res = control.create_spend(&destinations, &[dummy_op], 1).unwrap();
         assert!(res.psbt.inputs[0].non_witness_utxo.is_some());
         let tx = res.psbt.unsigned_tx;
@@ -1173,6 +1179,12 @@ mod tests {
             control.create_spend(&destinations, &[dummy_op], 1),
             Err(CommandError::AlreadySpent(dummy_op))
         );
+        // If we try to use coin selection, the spent coin will not be used as a candidate
+        // and so we get a coin selection error due to insufficient funds.
+        assert!(matches!(
+            control.create_spend(&destinations, &[], 1),
+            Err(CommandError::CoinSelectionError(..))
+        ));
 
         // We'd bail out if they tried to create a transaction with a too high feerate.
         let dummy_op_dup = bitcoin::OutPoint {
@@ -1196,6 +1208,71 @@ mod tests {
             )))
         );
 
+        // Add a confirmed unspent coin to be used for coin selection.
+        let confirmed_op_1 = bitcoin::OutPoint {
+            txid: dummy_op.txid,
+            vout: dummy_op.vout + 100,
+        };
+        db_conn.new_unspent_coins(&[Coin {
+            outpoint: confirmed_op_1,
+            is_immature: false,
+            block_info: Some(BlockInfo {
+                height: 174500,
+                time: 174500,
+            }),
+            amount: bitcoin::Amount::from_sat(80_000),
+            derivation_index: bip32::ChildNumber::from(42),
+            is_change: false,
+            spend_txid: None,
+            spend_block: None,
+        }]);
+        // Coin selection error due to insufficient funds.
+        assert!(matches!(
+            control.create_spend(&destinations, &[], 1),
+            Err(CommandError::CoinSelectionError(..))
+        ));
+        // Set destination amount equal to value of confirmed coins.
+        *destinations.get_mut(&dummy_addr).unwrap() = 80_000;
+        // Coin selection error occurs due to insufficient funds to pay fee.
+        assert!(matches!(
+            control.create_spend(&destinations, &[], 1),
+            Err(CommandError::CoinSelectionError(..))
+        ));
+        let confirmed_op_2 = bitcoin::OutPoint {
+            txid: confirmed_op_1.txid,
+            vout: confirmed_op_1.vout + 10,
+        };
+        // Add new confirmed coin to cover the fee.
+        db_conn.new_unspent_coins(&[Coin {
+            outpoint: confirmed_op_2,
+            is_immature: false,
+            block_info: Some(BlockInfo {
+                height: 174500,
+                time: 174500,
+            }),
+            amount: bitcoin::Amount::from_sat(20_000),
+            derivation_index: bip32::ChildNumber::from(43),
+            is_change: false,
+            spend_txid: None,
+            spend_block: None,
+        }]);
+        let res = control.create_spend(&destinations, &[], 2).unwrap();
+        let tx = res.psbt.unsigned_tx;
+        let mut tx_prev_outpoints = tx
+            .input
+            .iter()
+            .map(|txin| txin.previous_output)
+            .collect::<Vec<OutPoint>>();
+        tx_prev_outpoints.sort();
+        assert_eq!(tx.input.len(), 2);
+        assert_eq!(tx_prev_outpoints, vec![confirmed_op_1, confirmed_op_2]);
+        assert_eq!(tx.output.len(), 2);
+        assert_eq!(
+            tx.output[0].script_pubkey,
+            dummy_addr.payload.script_pubkey()
+        );
+        assert_eq!(tx.output[0].value, 80_000);
+
         // Can't create a transaction that spends an immature coinbase deposit.
         let imma_op = bitcoin::OutPoint::from_str(
             "4753a1d74c0af8dd0a0f3b763c14faf3bd9ed03cbdf33337a074fb0e9f6c7810:0",