add Opcode.smallInt()

lib/opcode.js

@@ -46,6 +46,16 @@ Opcode.prototype.toString = function() {
   return str;
 };
 
+Opcode.smallInt = function(n) {
+  if (!(n >= 0 && n <= 16)) {
+    throw new Error('Invalid Argument: n must be between 0 and 16');
+  }
+  if (n === 0) {
+    return Opcode('OP_0');
+  }
+  return new Opcode(Opcode.map.OP_1 + n - 1);
+};
+
 Opcode.map = {
   // push value
   OP_FALSE: 0,

test/opcode.js

@@ -92,13 +92,22 @@ describe('Opcode', function() {
     Opcode('OP_16')
   ];
 
+  describe('@smallInt', function() {
+    var testSmallInt = function(n, op) {
+      Opcode.smallInt(n).toString().should.equal(op.toString());
+    };
+    for (var i = 0; i < smallints.length; i++) {
+      var op = smallints[i];
+      it('should work for small int ' + op, testSmallInt.bind(null, i, op));
+    }
+  });
   describe('@isSmallIntOp', function() {
-    var testSmallInt = function() {
-      Opcode.isSmallIntOp(this).should.equal(true);
+    var testIsSmallInt = function(op) {
+      Opcode.isSmallIntOp(op).should.equal(true);
     };
     for (var i = 0; i < smallints.length; i++) {
       var op = smallints[i];
-      it('should work for small int ' + op, testSmallInt.bind(op));
+      it('should work for small int ' + op, testIsSmallInt.bind(null, op));
     }
 
     it('should work for non-small ints', function() {