A gem providing "time travel" and "time freezing" capabilities, making it dead simple to test time-dependent code. It provides a unified method to mock Time.now, Date.today, and DateTime.now in a single call.
factory_bot provides a framework and DSL for defining and using factories - less error-prone, more explicit, and all-around easier to work with than fixtures.
Fabrication is an object generation framework for ActiveRecord, Mongoid, Sequel, or any other Ruby object.
WebMock allows stubbing HTTP requests and setting expectations on HTTP requests.
Record your test suite's HTTP interactions and replay them during future test runs for fast, deterministic, accurate tests.
Capybara is an integration testing tool for rack based web applications. It simulates how a user would interact with a website
Selenium implements the W3C WebDriver protocol to automate popular browsers. It aims to mimic the behaviour of a real user as it interacts with the application's HTML. It's primarily intended for web application testing, but any web-based task can automated.