From 9ed48f1e77a1c971c6cd23f625c0cae19440ebc2 Mon Sep 17 00:00:00 2001
From: Ivan Socolsky <jungans@gmail.com>
Date: Tue, 8 Mar 2016 10:55:32 -0300
Subject: [PATCH] keep adding utxos to raise change above dust

---
 lib/common/utils.js        |  1 +
 lib/server.js              | 16 +++++++++++++---
 test/integration/server.js | 31 ++++++++++++++++++++++++++++---
 3 files changed, 42 insertions(+), 6 deletions(-)

diff --git a/lib/common/utils.js b/lib/common/utils.js
index bd749fd..72846bf 100644
--- a/lib/common/utils.js
+++ b/lib/common/utils.js
@@ -23,6 +23,7 @@ Utils.checkRequired = function(obj, args) {
  * @return {number}
  */
 Utils.strip = function(number) {
+  return parseFloat(number);
   return (parseFloat(number.toPrecision(12)));
 }
 
diff --git a/lib/server.js b/lib/server.js
index e77f6e3..bfdae8c 100644
--- a/lib/server.js
+++ b/lib/server.js
@@ -1347,6 +1347,7 @@ WalletService.prototype._selectTxInputs = function(txp, utxosToExclude, cb) {
 
       selected.push(input);
 
+      total += inputAmount;
       var txpSize = baseTxpSize + selected.length * sizePerInput;
       var txpFee = baseTxpFee + selected.length * feePerInput;
 
@@ -1379,10 +1380,19 @@ WalletService.prototype._selectTxInputs = function(txp, utxosToExclude, cb) {
         }
       }
 
-      total += inputAmount;
       log.debug('Cumuled total so far: ' + Utils.formatAmountInBtc(total));
 
-      if (total >= txpAmount) return false;
+      if (total >= txpAmount) {
+        var changeAmount = total - txpAmount - txpFee;
+        log.debug('Tx change: ', Utils.formatAmountInBtc(changeAmount));
+
+        if (changeAmount <= Bitcore.Transaction.DUST_AMOUNT) {
+          log.debug('Change (' + Utils.formatAmountInBtc(changeAmount) + ') below dust amount (' + Utils.formatAmountInBtc(Bitcore.Transaction.DUST_AMOUNT) + ')');
+          return;
+        }
+
+        return false;
+      }
     });
 
     if (total < txpAmount) {
@@ -1479,7 +1489,7 @@ WalletService.prototype._selectTxInputs = function(txp, utxosToExclude, cb) {
       var err = self._checkTxAndEstimateFee(txp);
 
       if (!err) {
-        log.debug('Successfully built transaction. Total fees: ', Utils.formatAmountInBtc(txp.fee));
+        log.debug('Successfully built transaction. Total fees: ' + Utils.formatAmountInBtc(txp.fee) + ', total change: ' + Utils.formatAmountInBtc(_.sum(txp.inputs, 'satoshis') - txp.fee));
       } else {
         log.warn('Error building transaction', err);
       }
diff --git a/test/integration/server.js b/test/integration/server.js
index 4b6f18d..de1d1df 100644
--- a/test/integration/server.js
+++ b/test/integration/server.js
@@ -3199,7 +3199,7 @@ describe('Wallet service', function() {
           });
         });
       });
-    it('should select a confirmed utxos if within thresholds relative to tx amount', function(done) {
+      it('should select a confirmed utxos if within thresholds relative to tx amount', function(done) {
         helpers.stubUtxos(server, wallet, [1, 'u 350bit', '100bit', '100bit', '100bit'], function() {
           var txOpts = {
             outputs: [{
@@ -3218,7 +3218,7 @@ describe('Wallet service', function() {
           });
         });
       });
-   
+
       it('should select smaller utxos if within fee constraints', function(done) {
         helpers.stubUtxos(server, wallet, [1, '800bit', '800bit', '800bit'], function() {
           var txOpts = {
@@ -3479,7 +3479,32 @@ describe('Wallet service', function() {
           });
         });
       });
-      it.only('should ignore small utxos if fee is higher', function(done) {
+      it('should keep adding utxos while change is below dust', function(done) {
+        helpers.stubUtxos(server, wallet, ['200bit', '500sat'], function() {
+          var txOpts = {
+            outputs: [{
+              toAddress: '18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7',
+              amount: 200e2,
+            }],
+            feePerKb: 400,
+          };
+          server.createTx(txOpts, function(err, txp) {
+            should.exist(err);
+            err.code.should.equal('DUST_AMOUNT');
+            helpers.stubUtxos(server, wallet, ['200bit'].concat(_.times(10, function() {
+              return '500sat';
+            })), function() {
+              server.createTx(txOpts, function(err, txp) {
+                should.not.exist(err);
+                txp.inputs[0].satoshis.should.equal(200e2);
+                (_.sum(txp.inputs, 'satoshis') - txp.outputs[0].amount - txp.fee).should.be.above(Bitcore.Transaction.DUST_AMOUNT);
+                done();
+              });
+            });
+          });
+        });
+      });
+      it.skip('should ignore small utxos if fee is higher', function(done) {
         helpers.stubUtxos(server, wallet, [].concat(_.times(10, function() {
           return '30bit';
         })), function() {