Get tests to pass locally

[shioyama]

This gem is currently pretty hard to use locally since the test setup has gone stale. I made some changes that allow me to run the tests with bundle exec rake test:

# Running:

..................................

Fabulous run in 0.074798s, 454.5576 runs/s, 1871.7078 assertions/s.

34 runs, 140 assertions, 0 failures, 0 errors, 0 skips

[nvasilevski]

Let's do 3.4.1 as preview2 must be our internal version which is not helpful for an open-source gem