Unknown provider error in ngUpgrade (Angular 1/2 hybrid application)

[Stuart Updegrave]

I'm starting on a new project forked from an existing Angular 1 codebase, with the intention of using ngUpgrade to do new development using Angular 2. I've successfully added Angular 2 to the project, but when I try to instantiate ngUpgrade in order to bootstrap the ng2 side of the application, I get the following error:

zone.js:461 Unhandled Promise rejection: Error: [$injector:modulerr] Failed to instantiate module NG2_UPGRADE_0_ due to:

  Error: [$injector:unpr] Unknown provider: $$testabilityProvider

  http://errors.angularjs.org/1.2.15-build.2399+sha.ca4ddfa/$injector/unpr?p0=%24%24testabilityProvider

      at http://localhost:63342/myapp/bower_components/angular/angular.js:78:12

      at http://localhost:63342/myapp/bower_components/angular/angular.js:3596:19

      at Object.getService [as get] (http://localhost:63342/myapp/bower_components/angular/angular.js:3723:39)

      at Object.decorator (http://localhost:63342/myapp/bower_components/angular/angular.js:3652:41)

      at eval (http://localhost:63342/myapp/node_modules/@angular/upgrade/src/upgrade_adapter.js:309:25)

      at http://localhost:63342/myapp/bower_components/angular/angular.js:3679:37

      at Array.forEach (native)

      at forEach (http://localhost:63342/myapp/bower_components/angular/angular.js:322:11)

      at loadModules (http://localhost:63342/myapp/bower_components/angular/angular.js:3666:5)

      at createInjector (http://localhost:63342/myapp/bower_components/angular/angular.js:3606:11)

  http://errors.angularjs.org/1.2.15-build.2399+sha.ca4ddfa/$injector/moduler…FSSMS%2FClient%2Fapp%2Fbower_components%2Fangular%2Fangular.js%3A3606%3A11)

      at http://localhost:63342/myapp/bower_components/angular/angular.js:78:12

      at http://localhost:63342/myapp/bower_components/angular/angular.js:3700:15

      at Array.forEach (native)

      at forEach (http://localhost:63342/myapp/bower_components/angular/angular.js:322:11)

      at loadModules (http://localhost:63342/myapp/bower_components/angular/angular.js:3666:5)

      at createInjector (http://localhost:63342/myapp/bower_components/angular/angular.js:3606:11)

      at doBootstrap (http://localhost:63342/myapp/bower_components/angular/angular.js:1338:20)

      at eval (http://localhost:63342/myapp/node_modules/@angular/upgrade/src/upgrade_adapter.js:348:42)

      at ZoneDelegate.invoke (http://localhost:63342/myapp/node_modules/zone.js/dist/zone.js:323:29)

      at Object.onInvoke (http://localhost:63342/myapp/node_modules/@angular/core/src/zone/ng_zone_impl.js:45:41)

  Error loading http://localhost:63342/myapp/ng2/main.js

I've searched for information on Failed to instantiate module NG2_UPGRADE_0_ and on $$testabilityProvider, but haven't been able to find anything useful.

It's a fairly complex project to start with, so trying to tear this down to a workable plunkr is challenging. Before I try to do so, is this something anyone has any ideas about?

Looking at the call stack, clearly the calls go from Angular 2 (node_modules/@angular/...) into angularjs (bower_components/angular), so the process appears to be starting off as expected. I don't have enough of an understanding of ngUpgrade to troubleshoot beyond what I've done so far. 

(This is cross-posted from http://stackoverflow.com/questions/37662930/unknown-provider-error-in-ngupgrade-angular-1-2-hybrid-application. I'm happy to accept a correct answer over there.) 

Hopefully someone has an idea - this has been blocking me for a couple of days now. 

Cheers,

Stuart