class ParallelTests::RSpec::Runner

def determine_executable
  cmd = case
  when File.exist?("bin/rspec")
    WINDOWS ? "ruby bin/rspec" : "bin/rspec"
  when ParallelTests.bundler_enabled?
    cmd = (run("bundle show rspec-core") =~ %r{Could not find gem.*} ? "spec" : "rspec")
    "bundle exec #{cmd}"
  else
    %w[spec rspec].detect{|cmd| system "#{cmd} --version > #{DEV_NULL} 2>&1" }
  end
  cmd or raise("Can't find executables rspec or spec")
end