#8511 Modernizes serve-test.js (#8570)
#8511 Modernizes serve-test.js (#8570)

* #8511 Modernizes serve-test.js

* Fixes prettier errors

* Removes unused import

jgwhite/ember-cli,raycohen/ember-cli,HeroicEric/ember-cli,ember-cli/ember-cli,HeroicEric/ember-cli,asakusuma/ember-cli,balinterdi/ember-cli,HeroicEric/ember-cli,jrjohnson/ember-cli,thoov/ember-cli,jrjohnson/ember-cli,balinterdi/ember-cli,buschtoens/ember-cli,buschtoens/ember-cli,jgwhite/ember-cli,elwayman02/ember-cli,thoov/ember-cli,HeroicEric/ember-cli,kategengler/ember-cli,kategengler/ember-cli,elwayman02/ember-cli,jgwhite/ember-cli,ember-cli/ember-cli,thoov/ember-cli,jgwhite/ember-cli,thoov/ember-cli,raycohen/ember-cli,asakusuma/ember-cli,ember-cli/ember-cli