To enable RSpec when you are using a C extension in a gem, just add something like this to your spec helper. It will build the C code every time you run `rspec`

spec_helper.rb

# Include C extension
puts 'Building C extension'

Dir.chdir('ext/hola') do
  output = `ruby extconf.rb`
  raise output unless $? == 0
  output = `make`
  raise output unless $? == 0
end

# Enables require 'hola/hola' in Ruby
$: << File.dirname(__FILE__) + '/../ext'

# Include Ruby code
require_relative '../lib/hola'