Context

• node version: 11.5.0
• joi version: 10.6.0
• environment (node, browser): node
• used with (hapi, standalone, ...): standalone

What are you trying to achieve or the steps to reproduce ?

Consider the following example code:

const joi = require('joi');
const obj = {foo: 'bar'};
Object.defineProperty(obj, 'test', { value: 42, enumerable: false });
joi.validate(obj, joi.object().keys({}).unknown()).value
// >> { foo: 'bar' }
joi.validate(obj, joi.object().keys({}).unknown()).value.test
// >> undefined

Which result you had ?

Joi strips non-enumerable properties of the object.

What did you expect ?

Unknown properties being allowed, the object should be returned unaffected. Own object properties should not be stripped from the returned value.

Use-case

I do have a validator that takes an object, and validates that one of its values is an ORM model:

Joi.object().type(MyModel)

This works fine. The ORM defines on the model a few methods, that are not enumerable, and these are kept at this point.

If, however, I try to validate one of the values of a model instance:

Joi.object().type(MyModel).keys({ something: Joi.string() }).unknown()

The ORM-defined methods are stripped from the resulting value.