feat: provide keys in default noUnknown message (#579)

Author: doomsower

src/locale.js

@@ -54,7 +54,7 @@ export let date = {
 export let boolean = {};
 
 export let object = {
-  noUnknown: '${path} field cannot have keys not specified in the object shape',
+  noUnknown: '${path} field has unspecified keys: ${unknown}',
 };
 
 export let array = {

src/object.js

@@ -240,8 +240,12 @@ inherits(ObjectSchema, MixedSchema, {
       exclusive: true,
       message: message,
       test(value) {
+        const unknownKeys = unknown(this.schema, value);
         return (
-          value == null || !noAllow || unknown(this.schema, value).length === 0
+          value == null ||
+          !noAllow ||
+          unknownKeys.length === 0 ||
+          this.createError({ params: { unknown: unknownKeys.join(', ') } })
         );
       },
     });

test/object.js

@@ -325,7 +325,7 @@ describe('Object types', () => {
         .validate({ extra: 'field' }, { strict: true })
         .should.be.rejected()
         .then(err => {
-          err.errors[0].should.be.a('string');
+          err.errors[0].should.be.a('string').that.include('extra');
         }),
     ]);
   });