Could not find module ember-testing imported from @ember/test/index

[elwayman02]

I'm seeing this error when deploying my addon's demo app to production after upgrading from 0.37 to 0.40 of @embroider/test-setup: elwayman02/ember-user-activity#419

Here's a live reproduction of the error, which can be seen in the browser console: https://ember-user-activity.jhawk.co/

Uncaught Error: Could not find module `ember-testing` imported from `@ember/test/index`
    at vendor-6e50465db379986591a65cb5508c4ddc.js:13
    at c (vendor-6e50465db379986591a65cb5508c4ddc.js:13)
    at s.findDeps (vendor-6e50465db379986591a65cb5508c4ddc.js:25)
    at c (vendor-6e50465db379986591a65cb5508c4ddc.js:13)
    at s.findDeps (vendor-6e50465db379986591a65cb5508c4ddc.js:25)
    at c (vendor-6e50465db379986591a65cb5508c4ddc.js:13)
    at s.findDeps (vendor-6e50465db379986591a65cb5508c4ddc.js:25)
    at c (vendor-6e50465db379986591a65cb5508c4ddc.js:13)
    at s.findDeps (vendor-6e50465db379986591a65cb5508c4ddc.js:25)
    at c (vendor-6e50465db379986591a65cb5508c4ddc.js:13)

If I rollback to 0.37, the app works as expected.

[rwjblue]

Fixed by emberjs/ember.js#19540 and released in 3.27.1.

[elwayman02]

So, just to clarify - even though this issue occurred on Ember 3.26 and was introduced by upgrading to @embroider/test-setup 0.40, the fix is to upgrade Ember? Does that mean the latest version of @embroider/test-setup is incompatible with Ember 3.26?