import node module in Ember test helper with ember-browserify

I want to pluralize the text inside a test helper I wrote.

I have installed my module with

yarn add pluralize --dev

and tried to import in my test helper with

import pluralize from 'npm:pluralize'

but it won't work. I have also tried absolute and relative paths to node_module, but nothing will work. I do not use this helper or the pluralization inside the actual app, only in the tests.