HDKeys: add toBuffer/fromBuffer to HDPublicKey

lib/hdpublickey.js

@@ -417,6 +417,25 @@ HDPublicKey.prototype.toJSON = function toJSON() {
   return JSON.stringify(this.toObject());
 };
 
+/**
+ * Create a HDPublicKey from a buffer argument
+ *
+ * @param {Buffer} arg
+ * @return {HDPublicKey}
+ */
+HDPublicKey.fromBuffer = function(arg) {
+  return new HDPublicKey(arg);
+};
+
+/**
+ * Return a buffer representation of the xpubkey
+ *
+ * @return {Buffer}
+ */
+HDPublicKey.prototype.toBuffer = function() {
+  return this._buffers.xpubkey;
+};
+
 HDPublicKey.Hardened = 0x80000000;
 HDPublicKey.RootElementAlias = ['m', 'M'];
 

test/hdprivatekey.js

@@ -262,7 +262,7 @@ describe('HDPrivate key interface', function() {
     });
   });
 
-  describe.only('conversion to/from buffer', function() {
+  describe('conversion to/from buffer', function() {
     var str = 'xprv9s21ZrQH143K3QTDL4LXw2F7HEK3wJUD2nW2nRk4stbPy6cq3jPPqjiChkVvvNKmPGJxWUtg6LnF5kejMRNNU3TGtRBeJgk33yuGBxrMPHi';
     it('should roundtrip to/from a buffer', function() {
       var priv = new HDPrivateKey(str);

test/hdpublickey.js

@@ -153,6 +153,17 @@ describe('HDPublicKey interface', function() {
     pubKey.inspect().should.equal('<HDPublicKey: ' + pubKey.xpubkey + '>');
   });
 
+  describe('conversion to/from buffer', function() {
+
+    it('should roundtrip to an equivalent object', function() {
+      var pubKey = new HDPublicKey(xpubkey);
+      var toBuffer = pubKey.toBuffer();
+      var fromBuffer = HDPublicKey.fromBuffer(toBuffer);
+      var roundTrip = new HDPublicKey(fromBuffer.toBuffer());
+      roundTrip.xpubkey.should.equal(xpubkey);
+    });
+  });
+
   describe('conversion to different formats', function() {
     var plainObject = {
       'network':'livenet',