Before v3.0, it used to be that to make a custom test helper available to testing code, you'd import it into tests/helpers/start-app.js. Now that the testing reorg with 3.0 has removed that file, where should those imports go?
FWIW the ember-cli docs still show the old, non-existent file: https://ember-cli.com/testing#single-helper-per-file (filed a GH issue here)
The source for this change is this RFC. Basically you can (and should) just
importyour custom helpers.