By extending minitest/spec HyperSpec provides a Ruby DSL for testing HTTP APIs from the "outside".

Webspicy helps testing web services as software operation black boxes

A tool for automated testing and debugging of automation scripts (e.g., Chef).

test-page helps you to write easily maintainable integration tests by using Watir, Selenium or any other testing library.

Simplify API integration testing with a succinct rspec DSL and generate Swagger files directly from your rspecs

An RSpec helper module for testing command-line tools.

Regression testing for data

The idea behind Ab Crunch is that basic performance metrics and standards should be effortless, first-class citizens in the development process, with frequent visibility and immediate feedback when performance issues are introduced. Ab Crunch uses Apache Bench to run various strategies for load ...

Simple load testing with EventMachine and PhantomJS/CasperJS

Like Rails' assert_difference, but more compact and readable syntax through hashes, testing ranges and improved error reporting.

Rack::TestApp is another testing helper library for Rack application. IMO it is more intuitive than Rack::Test.

Ruby gem to help testing i18n with Beaker

Package of helper steps for BDD testing with Cucumber

Puppet testing tool coupled with Beaker

A starter kit for testing BDD in rails

Command-line interface and Ruby client library for Blitz.io. Make load and performance testing a fun sport.

A Busser runner plugin for testing bash scripts

A Busser runner plugin for the minitest testing library

Typhoeus driver for Capybara, allowing testing of REST APIs

A collection of utility methods, mocks and methods for testing Cinch plugins