Enable virtual build for test mode

[rustworthy]

This is to be able to run end-to-end browser tests against a dev server build.

Looks like adonijs framework forces NODE_ENV to be test when running tests, I suppose this is important for some internal details or the framework or the test runner, so doing something like NODE_ENV=test npm run test or "patching" the test launch binary are not valid options.

[jarle]

Thanks! This seems to fix the build issues that have been happening.