[Bug] 3.26: Router is not setup in a non-application test

🐞 Describe the Bug

Ember 3.24 included a change that meant the router service automatically worked in non-application tests (i.e. no need for this.owner.setupRouter()) - this worked great in 3.25, but seems to have regressed in 3.26.

🔬 Minimal Reproduction

Run the tests in this repo: https://github.com/grayt0r/ember-router-setup-in-tests.

Relevant code changes are here.

😕 Actual Behavior

The router is not setup and the test fails with an error (the exact error depends on which router method the component calls):

Cannot read property 'generate' of undefined

🤔 Expected Behavior

The router is setup, the link is correctly rendered and the test passes.

🌍 Environment

• Ember: - v3.26.1

➕ Additional Context

The test passes if I downgrade to 3.25.4 or if I add this.owner.setupRouter() to the test setup.

I think it might be related to this change: https://github.com/emberjs/ember.js/pull/19405.

/cc @Ravenstine @rwjblue

[rwjblue]

Chatted with @Ravenstine about this today, they are going to work on a failing test reproduction first so we can figure out the right way to fix…

[grayt0r]

@chriskrycho sorry for the delay, but that fix appears to solve our issues, thank you very much! 🙌