parameter validator supports optional parameters

lib/utils/parameter-validator.js

@@ -3,9 +3,14 @@ var ParameterValidator = module.exports = {
     options = Utils._.extend({
       throwError: true,
       deprecated: false,
-      onDeprecated: console.log
+      onDeprecated: console.log,
+      optional: false
     }, options || {})
 
+    if (options.optional && (value === undefined)) {
+      return true
+    }
+
     if (value === undefined) {
       throw new Error('No value has been passed.')
     }
@@ -14,9 +19,9 @@ var ParameterValidator = module.exports = {
       throw new Error('No expectation has been passed.')
     }
 
-    validateDeprication(value, expectation, options)
-
-    return validate(value, expectation, options)
+    return false
+      || validateDeprication(value, expectation, options)
+      || validate(value, expectation, options)
   }
 }
 
@@ -32,6 +37,7 @@ var validateDeprication = function(value, expectation, options) {
   if (options.deprecated) {
     if (matchesExpectation(value, options.deprecated)) {
       options.onDeprecated("Deprecated!")
+      return true
     }
   }
 }

test/utils.test.js

@@ -169,6 +169,12 @@ describe(Support.getTestDialectTeaser("Utils"), function() {
         }).to.throw('No value has been passed.')
       })
 
+      it('does not throw an error if the value is not defined and the parameter is optional', function() {
+        expect(function() {
+          Utils.validateParameter(undefined, Object, { optional: true })
+        }).to.not.throw()
+      })
+
       it('throws an error if the expectation is not defined', function() {
         expect(function() {
           Utils.validateParameter(1)