Added precondition to transaction.to for a positive integer as an amount

lib/transaction/transaction.js

@@ -639,6 +639,10 @@ Transaction.prototype.getChangeOutput = function() {
  * @return {Transaction} this, for chaining
  */
 Transaction.prototype.to = function(address, amount) {
+  $.checkArgument(
+    JSUtil.isPositiveInteger(amount),
+    'Amount is expected to be a positive integer'
+  );
   this.addOutput(new Output({
     script: Script(new Address(address)),
     satoshis: amount

lib/util/js.js

@@ -68,5 +68,17 @@ module.exports = {
       });
     });
     return target;
+  },
+  /**
+   * Checks that a value is a positive integer
+   *
+   * @param {*} value
+   * @return {Boolean}
+   */
+  isPositiveInteger: function isPositiveInteger(value) {
+    return typeof value === 'number' &&
+      isFinite(value) &&
+      Math.floor(value) === value &&
+      value >= 0;
   }
 };

test/transaction/transaction.js

@@ -50,9 +50,10 @@ describe('Transaction', function() {
     object.outputs[0].satoshis.should.equal(testAmount - 10000);
   });
 
-  it('can take a string argument as an amount', function() {
-    var stringTx = new Transaction().to('mrU9pEmAx26HcbKVrABvgL7AwA5fjNFoDc', '10000');
-    (stringTx.outputAmount).should.equal(10000);
+  it('will not accept NaN as an amount', function() {
+    (function() {
+      var stringTx = new Transaction().to('mrU9pEmAx26HcbKVrABvgL7AwA5fjNFoDc', NaN);
+    }).should.throw('Amount is expected to be a positive integer');
   });
 
   it('returns the fee correctly', function() {

test/util/js.js

@@ -32,4 +32,47 @@ describe('js utils', function() {
 
   });
 
+  describe('isPositiveInteger', function() {
+    it('false for float', function() {
+      var a = JSUtil.isPositiveInteger(0.1);
+      a.should.equal(false);
+    });
+
+    it('false for string float', function() {
+      var a = JSUtil.isPositiveInteger('0.1');
+      a.should.equal(false);
+    });
+
+    it('false for string integer', function() {
+      var a = JSUtil.isPositiveInteger('1');
+      a.should.equal(false);
+    });
+
+    it('false for negative integer', function() {
+      var a = JSUtil.isPositiveInteger(-1);
+      a.should.equal(false);
+    });
+
+    it('false for negative integer string', function() {
+      var a = JSUtil.isPositiveInteger('-1');
+      a.should.equal(false);
+    });
+
+    it('false for infinity', function() {
+      var a = JSUtil.isPositiveInteger(Infinity);
+      a.should.equal(false);
+    });
+
+    it('false for NaN', function() {
+      var a = JSUtil.isPositiveInteger(NaN);
+      a.should.equal(false);
+    });
+
+    it('true for positive integer', function() {
+      var a = JSUtil.isPositiveInteger(1000);
+      a.should.equal(true);
+    });
+
+  });
+
 });