I recently learned about a feature of ember-cli that allows for an addon to include content only in the test environment. Brian Cardarella pointed out in one of the addons that I work on that the test helper functions were getting included into the main build of any app including this addon. Since these were truly test helper functions, we required the functions exclusively in testing.
If you desire to only have content from your addon accessible in testing, you
can put all the content into the
test-support/ directory. When the addon is
included into the main app, it will get merged into the
tests/ directory of the
including app and not included when doing a build other than test.