- prevents apps from forever poisoning the ENV by doing bad things (something overrides PATH/HOME etc)
- allows use of Dotenv to load new ENV settings from disk (they do not override)
Test:
```
puts "THIS SHOULD CHANGE #{ENV["TEST"] ||= rand.to_s}"
```
then restart the server
* Bump minitest version.
* Add basic test helper file.
* Use minitest for web server tests.
* Use Minitest for unix socket tests.
* Use Minitest for ThreadPool tests.
* Use Minitest for TCP-Rack tests
* Use Minitest for TCPLogger tests.
* Add missing helper to test helpers.
* Use Minitest for Rack server tests.
* Use Minitest for Rack handler tests.
* Use Minitest for Puma::Server tests.
* Use Minitest for Puma::Server with SSL tests.
* Use Minitest for persisten connections tests.
* Require puma in test_helper file.
* Use minitest for Puma::NullIO tests.
* Remove unnecessary requires on test files.
* Use Minitest for MiniSSL tests.
* Use Minitest for IOBuffer tests.
* Require bundler/setup in Rakefile.
* Use Minitest for HttpParser tests.
* Use Minitest for Puma::Configuration tests.
* Use Minitest for Puma::CLI tests.
* Bump Minitest version for Ruby 2.1 Gemfile.
* Use Minitest for integration tests.
* Use Minitest for Puma::App::Status tests.
* Remove test-unit from Gemfiles.
* Add timeout helper to Minitest::Test.
* Use Minitest for Puma::Binder tests.
* Remove testhelp file.
* Add missing require to Puma::Binder tests.
* Prefer require instead of require_relative.
