Service injection in integration tests does not work

[mydea]

I have a component test like this:

let userSession = Ember.Service.extends({
    language: "en",
    dateFormat: "YYYY-MM-DD",
    fullDateFormat: "YYYY-MM-DD"
});

moduleForComponent('/auction-list-item', 'Integration | Component | auction list item', {
    integration: true,

    beforeEach: function () {
        this.register('service:user-session', userSession);
        this.inject.service('user-session', { as: 'userSession' });
    }
});

test('it renders', function (assert) {
    let auction = Ember.Object.create({
      // ...
    });

    console.log(this.get("userSession.fullDateFormat"));
    this.set("myAuction", auction);

    this.render(hbs`{{auction-list-item auction=myAuction}}`); 

    //...
});

Apparently, the service is not really overwritten. The console.log outputs the correct, overwritten value, however the component itself does not seem to use the injected session. My component is basically empty (the userSession-service is injected in a initializer into all components).

I created a small repo reproducing the issue with a minimal setup:
https://github.com/mydea/ember-cli-example-app-for-github/tree/integration-test-service-injection

There I have a simple component, where I inject a service and output a simple property. In my component integration test, I overwrite the service, but the output of the component is not actually changed.

[rwjblue]

Your reproduction made tracking this down a bit easier, thank you!!

This is the same underlying issue as these:

• Implicit service injection fails in unit tests for dasherized names ember-test-helpers#108
• https://github.com/rwjblue/ember-qunit/issues/199

I've got a solution that I am working on, and will close this in favor of tracking in emberjs/ember-test-helpers#108 (because the issue is ultimately upstream in ember-test-helpers).