I'm using some helpers defined by an Ember CLI Addon and everything works automatically in the Ember app itself but unit testing using ember-qunit is a bit tricky.
According to the ember-qunit doc, dependencies can be specified in needs like this:
needs: ['helper:ember-truth-helpers/helpers/eq']
I get a helper cannot be found error. I can understand the resolver is trying to find the helper within the app itself and helpers registered by an Addon is not found.
A workaround suggested by ember-truth-helpers author is to manually import and register any used helper before running each test case. This is cumbersome and less magical than how an Ember app can resolve things correctly.