We need to import '@embroider/macros/src/vendor/embroider-macros-test-support' in order to override isTesting / sync it with tests

Author: NullVoxPopuli

files/tests/index.html

@@ -17,6 +17,7 @@
     <script src="/testem.js" integrity="" data-embroider-ignore></script>
     <script type="module">
       import "ember-testing";
+      import "@embroider/macros/src/vendor/embroider-macros-test-support";
     </script>
 
     <script type="module">