implemented test encode method

package.json

@@ -30,7 +30,8 @@
   "homepage": "https://github.com/cryptocoinjs/hdkey",
   "devDependencies": {
     "terst": "^0.1.0",
-    "mocha": "^1.19.0"
+    "mocha": "^1.19.0",
+    "bs58": "^1.0.0"
   },
   "dependencies": {
     "sha512": "0.0.1"

test/hdkey.test.js

@@ -1,10 +1,14 @@
+var crypto = require('crypto')
+var bs58 = require('bs58')
 var HDKey = require('../')
 var fixtures = require('./fixtures')
 
 require('terst')
 
 function encode(buf) {
-  
+  var hash = crypto.createHash('sha256').update(buf).digest()
+  var chksum = crypto.createHash('sha256').update(hash).digest().slice(0,4)
+  return bs58.encode(Buffer.concat([buf, chksum]))
 }
 
 describe('hdkey', function() {