fix tx creation

lib/server.js

@@ -477,14 +477,11 @@ WalletService.prototype._selectTxInputs = function(txp, cb) {
 
     var balance = self._totalizeUtxos(utxos);
 
-    var txMinAmount = txp.amount + Bitcore.Transaction.FEE_PER_KB;
-    if (balance.totalAmount < txMinAmount)
-      return cb(new ClientError('INSUFFICIENTFUNDS', 'Insufficient funds' + (balance.totalAmount >= txp.amount ? ' for fee' : '')));
-
-    if ((balance.totalAmount - balance.lockedAmount) < txMinAmount)
+    if (balance.totalAmount < txp.amount)
+      return cb(new ClientError('INSUFFICIENTFUNDS', 'Insufficient funds'));
+    if ((balance.totalAmount - balance.lockedAmount) < txp.amount)
       return cb(new ClientError('LOCKEDFUNDS', 'Funds are locked by pending transaction proposals'));
 
-
     utxos = _.reject(utxos, {
       locked: true
     });
@@ -493,30 +490,39 @@ WalletService.prototype._selectTxInputs = function(txp, cb) {
     var total = 0;
     var selected = [];
     var inputs = _.sortBy(utxos, 'amount');
-    var bitcoreTx;
+    var bitcoreTx, bitcoreError;
 
     while (i < inputs.length) {
       selected.push(inputs[i]);
       total += inputs[i].satoshis;
+      i++;
 
-      if (total >= txMinAmount) {
+      if (total >= txp.amount) {
         try {
-          // Check if there are enough fees
           txp.inputs = selected;
           bitcoreTx = txp.getBitcoreTx();
-          txp.inputPaths = _.pluck(txp.inputs, 'path');
-          txp.fee = bitcoreTx.getFee();
-          return cb();
-        } catch (ex) {
-          if (ex.name != 'bitcore.ErrorTransactionFeeError') {
-            return cb(ex);
+          bitcoreError = bitcoreTx.getSerializationError({
+            disableIsFullySigned: true,
+          });
+          if (!bitcoreError) {
+            txp.inputPaths = _.pluck(txp.inputs, 'path');
+            txp.fee = bitcoreTx.getFee();
+            return cb();
           }
+        } catch (ex) {
+          return cb(ex);
         }
       }
-      i++;
     };
 
-    return cb(new ClientError('INSUFFICIENTFUNDS', 'Insufficient funds for fee'));
+    if (bitcoreError instanceof Bitcore.errors.Transaction.FeeError) {
+      return cb(new ClientError('INSUFFICIENTFUNDS', 'Insufficient funds for fee'));
+    }
+    if (bitcoreError instanceof Bitcore.errors.Transaction.DustOutputs) {
+      return cb(new ClientError('DUSTAMOUNT', 'Amount below dust threshold'));
+    }
+
+    return cb(error);
   });
 };
 

test/integration/server.js

@@ -956,6 +956,22 @@ describe('Copay server', function() {
       });
     });
 
+    it('should fail to create tx that would return change for dust amount', function(done) {
+      helpers.stubUtxos(server, wallet, [1], function() {
+        var fee = Bitcore.Transaction.FEE_PER_KB / 1e8;
+        var change = 0.00000001;
+        var amount = 1 - fee - change;
+
+        var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', amount, null, TestData.copayers[0].privKey_1H_0);
+        server.createTx(txOpts, function(err, tx) {
+          should.exist(err);
+          err.code.should.equal('DUSTAMOUNT');
+          err.message.should.equal('Amount below dust threshold');
+          done();
+        });
+      });
+    });
+
     it('should fail with different error for insufficient funds and locked funds', function(done) {
       helpers.stubUtxos(server, wallet, [10, 10], function() {
         var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 11, null, TestData.copayers[0].privKey_1H_0);
@@ -977,20 +993,18 @@ describe('Copay server', function() {
       });
     });
 
-    it('should fail with insufficient funds if fee is too large', function(done) {
-      helpers.stubUtxos(server, wallet, 10, function() {
-        var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', 9, null, TestData.copayers[0].privKey_1H_0);
-
-        var txpStub = sinon.stub(TxProposal.prototype, 'getBitcoreTx').throws({
-          name: 'bitcore.ErrorTransactionFeeError'
-        });
+    it('should create tx with 0 change output', function(done) {
+      helpers.stubUtxos(server, wallet, [1], function() {
+        var fee = Bitcore.Transaction.FEE_PER_KB / 1e8;
+        var amount = 1 - fee;
 
+        var txOpts = helpers.createProposalOpts('18PzpUFkFZE8zKWUPvfykkTxmB9oMR8qP7', amount, null, TestData.copayers[0].privKey_1H_0);
         server.createTx(txOpts, function(err, tx) {
-          should.exist(err);
-          err.code.should.equal('INSUFFICIENTFUNDS');
-          err.message.should.equal('Insufficient funds for fee');
-
-          txpStub.restore();
+          should.not.exist(err);
+          should.exist(tx);
+          var bitcoreTx = tx.getBitcoreTx();
+          bitcoreTx.outputs.length.should.equal(1);
+          bitcoreTx.outputs[0].satoshis.should.equal(tx.amount);
           done();
         });
       });