Unable to Import Transition Controller

[ionitron-bot]

Original issue by @Maraket on 2018-05-15T07:06:18Z

Ionic version: (check one with "x")
[ ] 1.x
[ ] 2.x
[x] 3.x

I'm submitting a ... (check one with "x")
[x] bug report
[ ] feature request
[ ] support request => Please do not submit support requests here, use one of these channels: https://forum.ionicframework.com/ or http://ionicworldwide.herokuapp.com/

Current behavior:
I am currently trying to extend the Tabs component for a project, and in doing so need to extend the Tab component. Though in extending, I had to put in my own reference to my extended Tabs component to pass in, this exposing the need to refer to the TransitionController which is not available to be imported outside of the ionic module.

I have attempted to create a mock TransitionController, but find that I am funning into the same error:

ionic-team/ionic-framework#5331
trades-tab.zip

Expected behavior:
Be able to import TransitionController (or I might not be using providers in the right way).

Other Info:
Found ionic-team/ionic-framework#10264 though found that the unit testing framework provided in ionic-team/ionic-framework#5331 doesn't include suggestions on how to mock TransitionController

Potential fix: Add export { TransitionController } from './transitions/transition-controller'; in ionic/src/index.ts.
Ionic Framework Version: 3.9.2
Ionic CLI Version: 3.20.0
OS: Ubuntu 16.04
Node Version: v8.11.0