Revert "spend: add 10 sats to fee for 1 sat/vb txs"

This reverts commit 74a53ba.

I also removed the extra sats being added in the functional test.

src/commands/mod.rs

@@ -1497,7 +1497,7 @@ mod tests {
 
         // Transaction is 1 in (P2WSH satisfaction), 2 outs. At 1sat/vb, it's 161 sats fees.
         // At 2sats/vb, it's twice that.
-        assert_eq!(tx.output[1].value.to_sat(), 89_829);
+        assert_eq!(tx.output[1].value.to_sat(), 89_839);
         let psbt = if let CreateSpendResult::Success { psbt, .. } = control
             .create_spend(&destinations, &[dummy_op], 2, None)
             .unwrap()
@@ -1565,18 +1565,18 @@ mod tests {
             dummy_addr.payload().script_pubkey()
         );
         assert_eq!(tx.output[0].value.to_sat(), 95_000);
-        // change = 100_000 - 95_000 - /* fee without change */ 128 - /* extra fee for change output */ 43 = 4829
+        // change = 100_000 - 95_000 - /* fee without change */ 127 - /* extra fee for change output */ 43 = 4830
         assert_eq!(
             warnings,
             vec![
                 "Dust UTXO. The minimal change output allowed by Liana is 5000 sats. \
-                Instead of creating a change of 4829 sats, it was added to the \
+                Instead of creating a change of 4839 sats, it was added to the \
                 transaction fee. Select a larger input to avoid this from happening."
             ]
         );
 
         // Increase the target value by the change amount and the warning will disappear.
-        *destinations.get_mut(&dummy_addr).unwrap() = 95_000 + 4_829;
+        *destinations.get_mut(&dummy_addr).unwrap() = 95_000 + 4_839;
         let (psbt, warnings) = if let CreateSpendResult::Success { psbt, warnings } = control
             .create_spend(&destinations, &[dummy_op], 1, None)
             .unwrap()
@@ -1591,7 +1591,7 @@ mod tests {
 
         // Now increase target also by the extra fee that was paying for change and we can still create the spend.
         *destinations.get_mut(&dummy_addr).unwrap() =
-            95_000 + 4_829 + /* fee for change output */ 43;
+            95_000 + 4_830 + /* fee for change output */ 43;
         let (psbt, warnings) = if let CreateSpendResult::Success { psbt, warnings } = control
             .create_spend(&destinations, &[dummy_op], 1, None)
             .unwrap()
@@ -1606,15 +1606,15 @@ mod tests {
 
         // Now increase the target by 1 more sat and we will have insufficient funds.
         *destinations.get_mut(&dummy_addr).unwrap() =
-            95_000 + 4_829 + /* fee for change output */ 43 + 1;
+            95_000 + 4_839 + /* fee for change output */ 43 + 1;
         assert_eq!(
             control.create_spend(&destinations, &[dummy_op], 1, None),
             Ok(CreateSpendResult::InsufficientFunds { missing: 1 }),
         );
 
         // Now decrease the target so that the lost change is just 1 sat.
         *destinations.get_mut(&dummy_addr).unwrap() =
-            100_000 - /* fee without change */ 128 - /* extra fee for change output */ 43 - 1;
+            100_000 - /* fee without change */ 118 - /* extra fee for change output */ 43 - 1;
         let warnings = if let CreateSpendResult::Success { warnings, .. } = control
             .create_spend(&destinations, &[dummy_op], 1, None)
             .unwrap()
@@ -1635,7 +1635,7 @@ mod tests {
 
         // Now decrease the target value so that we have enough for a change output.
         *destinations.get_mut(&dummy_addr).unwrap() =
-            95_000 - /* fee without change */ 128 - /* extra fee for change output */ 43;
+            95_000 - /* fee without change */ 118 - /* extra fee for change output */ 43;
         let (psbt, warnings) = if let CreateSpendResult::Success { psbt, warnings } = control
             .create_spend(&destinations, &[dummy_op], 1, None)
             .unwrap()
@@ -1651,7 +1651,7 @@ mod tests {
 
         // Now increase the target by 1 and we'll get a warning again, this time for 1 less than the dust threshold.
         *destinations.get_mut(&dummy_addr).unwrap() =
-            95_000 - /* fee without change */ 128 - /* extra fee for change output */ 43 + 1;
+            95_000 - /* fee without change */ 118 - /* extra fee for change output */ 43 + 1;
         let warnings = if let CreateSpendResult::Success { warnings, .. } = control
             .create_spend(&destinations, &[dummy_op], 1, None)
             .unwrap()

src/spend.rs

@@ -12,7 +12,6 @@ use bdk_coin_select::{
     metrics::LowestFee, Candidate, ChangePolicy, CoinSelector, DrainWeights, FeeRate, Replace,
     Target, TargetFee, TargetOutputs, TXIN_BASE_WEIGHT,
 };
-use log::info;
 use miniscript::bitcoin::{
     self,
     absolute::{Height, LockTime},
@@ -385,21 +384,9 @@ fn select_coins_for_spend(
         long_term_feerate,
     );
 
-    // FIXME: This is a quick change to avoid going below the min relay fee:
-    // If the required feerate is 1 sat/vb and this is not a replacement tx,
-    // use the replaced_fee parameter to ensure we pay at least 10 sats more
-    // than the size of the tx.
-    // E.g. if vsize = 186, the fee will be pay >= 196 sats.
-    let replaced_fee_modified = if replaced_fee.is_none() && feerate_vb_u32 == 1 {
-        info!("setting replaced fee to 10");
-        Some(10)
-    } else {
-        replaced_fee
-    };
-
     // Finally, run the coin selection algorithm. We use an opportunistic BnB and if it couldn't
     // find any solution we fall back to selecting coins by descending value.
-    let replace = replaced_fee_modified.map(Replace::new);
+    let replace = replaced_fee.map(Replace::new);
     let target_fee = TargetFee {
         rate: feerate,
         replace,

tests/test_spend.py

@@ -136,7 +136,7 @@ def sign_and_broadcast(psbt):
     res = lianad.rpc.createspend(destinations, [outpoint], 1)
     psbt = PSBT.from_base64(res["psbt"])
     sign_and_broadcast(psbt)
-    change_amount = 848 if USE_TAPROOT else 829
+    change_amount = 858 if USE_TAPROOT else 839
     assert len(psbt.o) == 1
     assert len(res["warnings"]) == 1
     assert (
@@ -155,7 +155,7 @@ def sign_and_broadcast(psbt):
     res = lianad.rpc.createspend(destinations, [outpoint_3], 1)
     psbt = PSBT.from_base64(res["psbt"])
     sign_and_broadcast(psbt)
-    change_amount = 836 if USE_TAPROOT else 817
+    change_amount = 846 if USE_TAPROOT else 827
     assert len(psbt.o) == 1
     assert len(res["warnings"]) == 1
     assert (
@@ -623,10 +623,6 @@ def test_tr_multisig_2_of_2_feerate_is_met(feerate, lianad_multisig_2_of_2, bitc
     spend_weight = res["weight"]
     assert spend_weight == 646
 
-    # Due to https://github.com/wizardsardine/liana/pull/1323 we currently
-    # add 10 sats if feerate is 1.
-    extra = 10 if feerate == 1 else 0
-
     # Note that due to https://github.com/wizardsardine/liana/issues/1132
     # we do not round up vbytes before multiplying by feerate.
-    assert spend_fee == math.ceil((646.0 / 4.0) * feerate) + extra
+    assert spend_fee == math.ceil((646.0 / 4.0) * feerate)