Script/Address: Add check for valid number of threshold needed

lib/script/script.js

@@ -543,6 +543,8 @@ Script.prototype.removeCodeseparators = function() {
  *                      public keys before creating the script
  */
 Script.buildMultisigOut = function(publicKeys, threshold, opts) {
+  $.checkArgument(threshold <= publicKeys.length,
+                  'Number of required signatures must be less than or equal to the number of public keys');
   opts = opts || {};
   var script = new Script();
   script.add(Opcode.smallInt(threshold));

test/address.js

@@ -499,6 +499,12 @@ describe('Address', function() {
       var address2 = Address.createMultisig(publics, 2);
       address.toString().should.equal(address2.toString());
     });
+
+    it('fails if invalid array is provided', function() {
+      expect(function() {
+        return Address.createMultisig([],3,'testnet');
+      }).to.throw('Number of required signatures must be less than or equal to the number of public keys');
+    });
   });
 
 });

test/script/script.js

@@ -430,6 +430,12 @@ describe('Script', function() {
       s.toString().should.equal('OP_2 33 0x021f2f6e1e50cb6a953935c3601284925decd3fd21bc445712576873fb8c6ebc18 33 0x022df8750480ad5b26950b25c7ba79d3e37d75f640f8e5d9bcd5b150a0f85014da 33 0x03e3818b65bcc73a7d64064106a859cc1a5a728c4345ff0b641209fba0d90de6e9 OP_3 OP_CHECKMULTISIG');
       s.isMultisigOut().should.equal(true);
     });
+    it('should fail when number of required signatures is greater than number of pubkeys', function() {
+      expect(sortkeys.length).to.equal(3);
+      expect(function() {
+        return Script.buildMultisigOut(sortkeys, 4);
+      }).to.throw('Number of required signatures must be less than or equal to the number of public keys');
+    });
     it('should create unsorted script if specified', function() {
       var s = Script.buildMultisigOut(sortkeys, 2);
       var u = Script.buildMultisigOut(sortkeys, 2, {