add async version of setUnspentOutputs

src/wallet.js

@@ -83,6 +83,16 @@ var Wallet = function (seed, options) {
       this.outputs = outputs
     }
 
+    this.setUnspentOutputsAsync = function(utxo, callback) {
+      try {
+        this.setUnspentOutputs(utxo)
+      } catch(err) {
+        return callback(err)
+      }
+
+      return callback()
+    }
+
     function outputToUnspentOutput(output){
       var hashAndIndex = output.receive.split(":")
 

test/wallet.js

@@ -273,6 +273,37 @@ describe('Wallet', function() {
         assert.equal(output.address, utxo[0].address)
       }
     })
+
+    describe('setUnspentOutputsAsync', function(){
+      var utxo;
+      beforeEach(function(){
+        utxo = cloneObject([expectedUtxo])
+      })
+
+      afterEach(function(){
+        wallet.setUnspentOutputs.restore()
+      })
+
+      it('calls setUnspentOutputs', function(){
+        sinon.stub(wallet, "setUnspentOutputs")
+
+        var callback = sinon.spy()
+        var tx = wallet.setUnspentOutputsAsync(utxo, callback)
+
+        assert(wallet.setUnspentOutputs.calledWith(utxo))
+        assert(callback.called)
+      })
+
+      it('when setUnspentOutputs throws an error, it invokes callback with error', function(){
+        sinon.stub(wallet, "setUnspentOutputs").throws()
+
+        var callback = sinon.spy()
+        var tx = wallet.setUnspentOutputsAsync(utxo, callback)
+
+        assert(callback.called)
+        assert(callback.args[0][0] instanceof Error)
+      })
+    })
   })
 
   describe('processTx', function(){