[fixed] camelcase should maintain leading underscores

Author: jquense

src/object.js

@@ -15,6 +15,13 @@ var MixedSchema = require('./mixed')
 
 let isRecursive = schema =>  (schema._subType || schema) === '$this'
 
+c.type('altCamel', function(str) {
+  let result = c.camel(str)
+    , idx = str.search(/[^_]/)
+
+  return idx === 0 ? result : (str.substr(0, idx) + result)
+})
+
 let childSchema = (field, parent) => {
   return isRecursive(field)
     ? field.of
@@ -215,7 +222,7 @@ inherits(ObjectSchema, MixedSchema, {
 
   camelcase(){
     return this.transform(obj => obj == null ? obj
-      : transform(obj, (newobj, val, key ) => newobj[c.camel(key)] = val))
+      : transform(obj, (newobj, val, key ) => newobj[c.altCamel(key)] = val))
   },
 
   constantcase(){

test/object.js

@@ -446,6 +446,15 @@ describe('Object types', function(){
       .cast(null)).to.equal(null)
   })
 
+  it('should camelCase with leading underscore', function(){
+    var inst = object().camelcase()
+
+    inst
+      .cast({ CON_STAT: 5, __isNew: true, __IS_FUN: true })
+      .should
+      .eql({ conStat: 5, __isNew: true, __isFun: true })
+  })
+
   it('should CONSTANT_CASE keys', function(){
     var inst = object().shape({
           CON_STAT: number(),