Validating path

Again through typeforce

src/hdnode.js

@@ -292,7 +292,7 @@ HDNode.prototype.isNeutered = function () {
 }
 
 HDNode.prototype.derivePath = function (path) {
-  typeforce(types.String, path)
+  typeforce(types.Path, path)
 
   var splitPath = path.split('/')
   if (splitPath[0] === 'm') {

src/types.js

@@ -26,6 +26,11 @@ function UInt53 (value) {
     Math.floor(value) === value
 }
 
+function Path (value) {
+  return typeforce.String(value) &&
+    value.match(/^([m]\/)?([0-9]+[']?\/)*([0-9]+[']?)$/)
+}
+
 // external dependent types
 var BigInt = typeforce.quacksLike('BigInteger')
 var ECPoint = typeforce.quacksLike('Point')
@@ -57,7 +62,8 @@ var types = {
   UInt8: UInt8,
   UInt31: UInt31,
   UInt32: UInt32,
-  UInt53: UInt53
+  UInt53: UInt53,
+  Path: Path
 }
 
 for (var typeName in typeforce) {

test/hdnode.js

@@ -312,8 +312,7 @@ describe('HDNode', function () {
 
             var pathSplit = path.split('/').slice(i + 2)
             var pathEnd = pathSplit.join('/')
-            var pathEndM = 'm/' + path
+            var pathEndM = 'm/' + pathEnd
-
             var child = cn.derivePath(pathEnd)
             verifyVector(child, cc, pathSplit.length + i + 1)
 
@@ -390,7 +389,7 @@ describe('HDNode', function () {
       }, /Expected UInt32/)
     })
 
-    it('throws on non-numbers', function () {
+    it('throws on wrong types', function () {
       var f = fixtures.valid[0]
       var master = HDNode.fromBase58(f.master.base58, NETWORKS_LIST)
 
@@ -406,6 +405,30 @@ describe('HDNode', function () {
       assert.throws(function () {
         master.derive('foo')
       }, /Expected UInt32/)
+      assert.throws(function () {
+        master.derivePath()
+      }, /Expected Path/)
+      assert.throws(function () {
+        master.derivePath(2)
+      }, /Expected Path/)
+      assert.throws(function () {
+        master.derivePath([2, 3, 4])
+      }, /Expected Path/)
+      assert.throws(function () {
+        master.derivePath('/')
+      }, /Expected Path/)
+      assert.throws(function () {
+        master.derivePath('m/m/123')
+      }, /Expected Path/)
+      assert.throws(function () {
+        master.derivePath('a/0/1/2')
+      }, /Expected Path/)
+      assert.throws(function () {
+        master.derivePath('m/0/  1  /2')
+      }, /Expected Path/)
+      assert.throws(function () {
+        master.derivePath('m/0/1.5/2')
+      }, /Expected Path/)
     })
   })
 })