You cannot use the same root element (#ember-testing) multiple times in an Ember.Application

We started getting this on the build server after 0.3.2 was published. Traced it back to ember-qunit and a downgrade to 0.3.1 which got our tests running successfully again. Here is the log

ok 8 PhantomJS 1.9 - JSHint - .: test-helper.js should pass jshint
not ok 9 PhantomJS 1.9 - AddressDisplayComponent: it renders

---
actual: >
null
message: >
TypeError: Requested keys of a value that is not an object.
Log: >
...
not ok 10 PhantomJS 1.9 - AddressDropdownComponent: it renders

---
actual: >
null
message: >
Error: Assertion Failed: You cannot use the same root element (#ember-testing) multiple times in an Ember.Application
Log: >
...
not ok 11 PhantomJS 1.9 - BackerTotalsComponent: it renders

---
actual: >
null
message: >
Error: Assertion Failed: You cannot use the same root element (#ember-testing) multiple times in an Ember.Application
Log: >
...
not ok 12 PhantomJS 1.9 - ConfirmProductComponent: it renders

---
actual: >
null
message: >
Error: Assertion Failed: You cannot use the same root element (#ember-testing) multiple times in an Ember.Application
Log: >
...
not ok 13 PhantomJS 1.9 - InputRegexComponent: it renders

---
actual: >
null
message: >
Error: Assertion Failed: You cannot use the same root element (#ember-testing) multiple times in an Ember.Application
Log: >

I’m not familiar enough with the changes in 0.3.2 to pinpoint the issue. I see some stuff was added for Glimmer (we’re on Ember 1.11.3)

[ef4]

To future visitor who land here from Google: this is an old thread with out-of-date advice. For example, in modern Ember you’re supposed to use module directly from QUnit, even though this thread calls that bad.

There are several reasons you might see “you cannot use the same root element” errors, mostly around broken tests leaving part of an application around to conflict with the next test.

[txm]

Ah ha thanks, test-support/helpers/start-app.js attributes.autoboot = true; // <------ true here.

Still the same num of test failing, but at least I can see for sure now that they are unhandled promise rejections.