Stub SailsJs helper function which is called with named arguments

**Node version**: 10.X
**Sails version** _(sails)_: 1.2.3

I'm trying to mock/stub a sailsjs helper function which is called with named arguments. Using `sinon` library for function mocking.

Example:

function call that needs to be mocked: `await sails.helpers.getData.with({})`

Tried Solutions:

1) `sinon.stub(sails.helpers, 'getData').returns(true)`

issue -> sails.helpers.getData.with is not a function

2) `sinon.stub(sails.helpers.getData, 'with').returns(true)`

issue -> Cannot redefine property: with

reason -> non-configurable property is set to false for sails object. And we can't change that.

3) Tried creating a fake function and adding it to `sails.helpers.getData['with']` property

4) Also tried setting special setters to `sails.helpers.getData` object with the help of rewire library.

What is the way to stub a helper which is called with named args.

Start from the reported call `sails.helpers.getData.with({})` and reproduce it with Node 10.x, Sails 1.2.3, Sinon, and the three stubbing approaches described. Trace how the named-argument helper is exposed and determine what a supported test double must preserve; done means a reproducible stubbing method or a clearly documented limitation.

Written by the indexing model from the issue text.