Add `uncheckedAddInput` function

* For internal usage: for example, testing Script.Interpreter

lib/transaction/transaction.js

@@ -414,9 +414,23 @@ Transaction.prototype.addInput = function(input, outputScript, satoshis) {
       satoshis: satoshis
     });
   }
+  return this.uncheckedAddInput(input);
+};
+
+/**
+ * Add an input to this transaction, without checking that the input has information about
+ * the output that it's spending.
+ *
+ * @param {Input} input
+ * @return Transaction this, for chaining
+ */
+Transaction.prototype.uncheckedAddInput = function(input) {
+  $.checkArgumentType(input, Input, 'input');
   this._changeSetup = false;
   this.inputs.push(input);
-  this._inputAmount += input.output.satoshis;
+  if (input.output) {
+    this._inputAmount += input.output.satoshis;
+  }
   return this;
 };
 

test/script/interpreter.js

@@ -202,7 +202,7 @@ describe('Interpreter', function() {
     var hashbuf = new Buffer(32);
     hashbuf.fill(0);
     var credtx = Transaction();
-    credtx.inputs.push(new Transaction.Input({
+    credtx.uncheckedAddInput(new Transaction.Input({
       prevTxId: '0000000000000000000000000000000000000000000000000000000000000000',
       outputIndex: 0xffffffff,
       sequenceNumber: 0xffffffff,
@@ -215,7 +215,7 @@ describe('Interpreter', function() {
     var idbuf = credtx.id;
 
     var spendtx = Transaction();
-    spendtx.inputs.push(new Transaction.Input({
+    spendtx.uncheckedAddInput(new Transaction.Input({
       prevTxId: idbuf.toString('hex'),
       outputIndex: 0,
       sequenceNumber: 0xffffffff,