_results

# for reference...
$ for i in 1 2 3 ; do time ruby config/application.rb >/dev/null ; done
ruby config/application.rb > /dev/null  1.89s user 0.27s system 99% cpu 2.171 total
ruby config/application.rb > /dev/null  1.86s user 0.26s system 99% cpu 2.125 total
ruby config/application.rb > /dev/null  1.84s user 0.26s system 99% cpu 2.113 total

$ for i in 1 2 3 ; do time bin/rake environment >/dev/null ; done
bin/rake environment > /dev/null  4.07s user 0.49s system 99% cpu 4.581 total
bin/rake environment > /dev/null  5.15s user 0.61s system 99% cpu 5.792 total
bin/rake environment > /dev/null  5.49s user 0.66s system 99% cpu 6.179 total

# normal Rails test task
$ for i in 1 2 3 ; do time bin/rake test >/dev/null ; done
bin/rake test > /dev/null  28.01s user 2.40s system 97% cpu 31.145 total
bin/rake test > /dev/null  28.80s user 2.51s system 97% cpu 32.099 total
bin/rake test > /dev/null  29.20s user 2.56s system 97% cpu 32.505 total

$ for i in 1 2 3 ; do time bin/rake test:combined >/dev/null ; done
bin/rake test:combined > /dev/null  15.58s user 1.04s system 97% cpu 16.984 total
bin/rake test:combined > /dev/null  15.60s user 1.03s system 98% cpu 16.953 total
bin/rake test:combined > /dev/null  15.71s user 1.05s system 97% cpu 17.106 total

$ for i in 1 2 3 ; do time script/test >/dev/null ; done
script/test > /dev/null  12.79s user 0.66s system 97% cpu 13.772 total
script/test > /dev/null  13.02s user 0.70s system 97% cpu 14.050 total
script/test > /dev/null  13.12s user 0.72s system 97% cpu 14.167 total

Rakefile

require File.expand_path('../config/application', __FILE__)
require 'rake'

My::Application.load_tasks

namespace :test do
  Rake::TestTask.new(:combined) do |t|
    t.libs << 'test'
    t.pattern = "test/**/*_test.rb"
  end
end

test

#!/bin/sh
ruby -Itest -Ilib -e "Dir[ARGV.pop].each {|f| require f }" './test/**/*_test.rb'