Creating ember addon for integration tests - can't get file into tests

(apologies for the title!)

I am trying to turn this:

http://ift.tt/1P54XSf

into an ember-cli-addon

I have read http://ift.tt/1RfoOgU which is great but I am stuck figuring out how to make the qunit-assert-html.min.js available in my tests.

All I have done so far is add the file to /vendor and then imported it inside index.js:

http://ift.tt/1P54XSh

npm linking the add-on into my project successfully adds the /vendor/qunit-assert-html.min.js to my apps /vendor folder but I can't figure out how to make that available in my integration tests.

Any help appreciated!