Hiera expresses Windows gem dependencies (in master branch only, but not yet released) but it only applies to ruby x86. When running on x64, the gem dependencies do not apply, so you can't use bundler to install gems, and run specs.
Currently, hiera's Gemfile uses the bundler `mingw` platform identifier, effectively:
Bundler::Dependency::PLATFORM_MAP maps that to the rubygems platform MINGW:
When run on ruby 1.9.3 x86, the MINGW gem platform is a match:
But on ruby 2 x64, it is not:
As a result, dependencies that are currently expressed for x86-mingw, do not apply when run on ruby 2 x64.