We got following error on travis now:
https://travis-ci.org/puma/puma/jobs/207434226
```
1) Error:
WebServerTest#test_simple_server:
NameError: uninitialized constant Net
/home/travis/build/puma/puma/test/test_helper.rb:24:in `block in hit'
/home/travis/build/puma/puma/test/test_helper.rb:20:in `each'
/home/travis/build/puma/puma/test/test_helper.rb:20:in `hit'
/home/travis/build/puma/puma/test/test_web_server.rb:36:in `test_simple_server'
```
I confirmed test passed with bundler 1.14.4 but errored with 1.14.5.
https://github.com/bundler/bundler/compare/v1.14.4...v1.14.5
The cause is 984f64d8a5
because `rubygems/spec_fetcher` requires `net/http` internally but is deferred now.
I think we should require stdlibs explicitly.
* 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.
