@ember/test-helpers v3 is requried, due to test-helpers depending on test-waiters, and this relationship requires ember-auto-import and test-helpers v3 has auto-import

Author: NullVoxPopuli

README.md

@@ -46,8 +46,9 @@ This addon implements the design specified in [RFC 581](https://github.com/ember
 
 ## Compatibility
 
-- Ember.js v2.18 or above
-- Ember CLI v2.13 or above
+- `ember-auto-import` or embroider 
+- `ember-source` v4 or above
+- `@ember/test-helpers` v3 or above
 
 ## Installation
 

test-apps/base-tests/config/ember-try.js

@@ -12,7 +12,7 @@ module.exports = async function () {
           devDependencies: {
             'ember-source': '~3.16.0',
             '@ember/string': '^3.0.0',
-            '@ember/test-helpers': '^2.9.3',
+            '@ember/test-helpers': '^3.0.0',
             '@glimmer/component': '^1.0.0',
             'ember-cli': '~3.28.0',
             'ember-cli-app-version': '^5.0.0',
@@ -27,7 +27,7 @@ module.exports = async function () {
           devDependencies: {
             'ember-source': '~3.28.11',
             '@ember/string': '^3.0.0',
-            '@ember/test-helpers': '^2.9.3',
+            '@ember/test-helpers': '^3.0.0',
             '@glimmer/component': '^1.0.0',
             'ember-cli': '~3.28.0',
             'ember-qunit': '^6.0.0',