HDPublicKey: Add precondition checks for static methods

lib/hdpublickey.js

@@ -1,6 +1,8 @@
 'use strict';
 
 var _ = require('lodash');
+var $ = require('./util/preconditions');
+
 var BN = require('./crypto/bn');
 var Base58 = require('./encoding/base58');
 var Base58Check = require('./encoding/base58check');
@@ -356,7 +358,18 @@ HDPublicKey._validateBufferArguments = function (arg) {
   }
 };
 
-HDPublicKey.fromString = HDPublicKey.fromObject = HDPublicKey.fromJSON = function(arg) {
+HDPublicKey.fromJSON = function(arg) {
+  $.checkArgument(JSUtil.isValidJSON(arg), 'No valid JSON string was provided');
+  return new HDPublicKey(arg);
+};
+
+HDPublicKey.fromObject = function(arg) {
+  $.checkArgument(_.isObject(arg), 'No valid argument was provided');
+  return new HDPublicKey(arg);
+};
+
+HDPublicKey.fromString = function(arg) {
+  $.checkArgument(_.isString(arg), 'No valid string was provided');
   return new HDPublicKey(arg);
 };
 

test/hdpublickey.js

@@ -122,7 +122,35 @@ describe('HDPublicKey interface', function() {
         return new HDPublicKey(buffers);
       }, errors.InvalidB58Checksum);
     });
+  });
 
+  describe('building with static methods', function() {
+    var expectStaticMethodFail = function(staticMethod, argument, message) {
+      expect(HDPublicKey[staticMethod].bind(null, argument)).to.throw(message);
+    };
+    it('fromJSON checks that a valid JSON is provided', function() {
+      var errorMessage = 'No valid JSON string was provided';
+      var method = 'fromJSON';
+      expectStaticMethodFail(method, undefined, errorMessage);
+      expectStaticMethodFail(method, null, errorMessage);
+      expectStaticMethodFail(method, 'invalid JSON', errorMessage);
+      expectStaticMethodFail(method, '{\'singlequotes\': true}', errorMessage);
+      expectStaticMethodFail(method, {}, errorMessage);
+    });
+    it('fromString checks that a string is provided', function() {
+      var errorMessage = 'No valid string was provided';
+      var method = 'fromString';
+      expectStaticMethodFail(method, undefined, errorMessage);
+      expectStaticMethodFail(method, null, errorMessage);
+      expectStaticMethodFail(method, {}, errorMessage);
+    });
+    it('fromObject checks that an object is provided', function() {
+      var errorMessage = 'No valid argument was provided';
+      var method = 'fromObject';
+      expectStaticMethodFail(method, undefined, errorMessage);
+      expectStaticMethodFail(method, null, errorMessage);
+      expectStaticMethodFail(method, '', errorMessage);
+    });
   });
 
   describe('error checking on serialization', function() {