Popular Ruby Gems projects

This gem provides a mitigation against CVE-2015-9284 (Cross-Site Request
Forgery on the request phrase when using OmniAuth gem with a Ruby on Rails
application) by implementing a CSRF token verifier that directly utilize
ActionController::RequestForgeryProtection code from Rails.

Pg is the Ruby interface to the PostgreSQL RDBMS. It works with PostgreSQL 9.3 and later.

minitest provides a complete suite of testing facilities supporting
TDD, BDD, mocking, and benchmarking.

"I had a class with Jim Weirich on testing last week and we were
 allowed to choose our testing frameworks. Kirk Haines and I were
 paired up and we cracked open the code for a few test
 frameworks...

 I MUST say that minitest is *very* readable / understandable
 compared to the 'other two' options we looked at. Nicely done and
 thank you for helping us keep our mental sanity."

-- Wayne E. Seguin

minitest/test is a small and incredibly fast unit testing framework.
It provides a rich set of assertions to make your tests clean and
readable.

minitest/spec is a functionally complete spec engine. It hooks onto
minitest/test and seamlessly bridges test assertions over to spec
expectations.

minitest/benchmark is an awesome way to assert the performance of your
algorithms in a repeatable manner. Now you can assert that your newb
co-worker doesn't replace your linear algorithm with an exponential
one!

minitest/mock by Steven Baker, is a beautifully tiny mock (and stub)
object framework.

minitest/pride shows pride in testing and adds coloring to your test
output. I guess it is an example of how to write IO pipes too. :P

minitest/test is meant to have a clean implementation for language
implementors that need a minimal set of methods to bootstrap a working
test suite. For example, there is no magic involved for test-case
discovery.

"Again, I can't praise enough the idea of a testing/specing
 framework that I can actually read in full in one sitting!"

-- Piotr Szotkowski

Comparing to rspec:

rspec is a testing DSL. minitest is ruby.

-- Adam Hawkins, "Bow Before MiniTest"

minitest doesn't reinvent anything that ruby already provides, like:
classes, modules, inheritance, methods. This means you only have to
learn ruby to use minitest and all of your regular OO practices like
extract-method refactorings still apply.

Jekyll is a simple, blog aware, static site generator.

Nokogiri (鋸) makes it easy and painless to work with XML and HTML from Ruby. It provides a
sensible, easy-to-understand API for reading, writing, modifying, and querying documents. It is
fast and standards-compliant by relying on native parsers like libxml2, libgumbo, or xerces.

Rack provides a minimal, modular and adaptable interface for developing
web applications in Ruby. By wrapping HTTP requests and responses in
the simplest way possible, it unifies and distills the API for web
servers, web frameworks, and software in between (the so-called
middleware) into a single method call.

Run Test::Unit / RSpec / Cucumber / Spinach in parallel

Code style checking for RSpec files.
A plugin for the RuboCop code style enforcing & linting tool.

Ruby applications tests profiling tools.

Contains tools to analyze factories usage, integrate with Ruby profilers,
profile your examples using ActiveSupport notifications (if any) and
statically analyze your code with custom RuboCop cops.

YARD is a documentation generation tool for the Ruby programming language.
It enables the user to generate consistent, usable documentation that can be
exported to a number of formats very easily, and also supports extending for
custom Ruby constructs such as custom class level definitions.

bundler-audit provides patch-level verification for Bundled apps.

Track and debug errors in your Ruby applications with ease using Rollbar. With this gem, you can easily monitor and report on exceptions and other errors in your code, helping you identify and fix issues more quickly. Rollbar's intuitive interface and advanced error tracking features make it the perfect tool for ensuring the stability and reliability of your Ruby applications.

A Ruby client that tries to match Redis' API one-to-one, while still
providing an idiomatic interface.

The Database Toolkit for Ruby

Curb (probably CUrl-RuBy or something) provides Ruby-language bindings for the libcurl(3), a fully-featured client-side URL transfer library. cURL and libcurl live at http://curl.haxx.se/

High-level wrapper for processing images for the web with ImageMagick or libvips.

Official AWS Ruby gem for Amazon Simple Email Service (Amazon SES). This gem is part of the AWS SDK for Ruby.

Provides binaries for WKHTMLTOPDF project in an easily accessible package.

Bundler manages an application's dependencies through its entire life, across many machines, systematically and repeatably

Wicked PDF uses the shell utility wkhtmltopdf to serve a PDF file to a user from HTML.
In other words, rather than dealing with a PDF generation DSL of some sort,
you simply write an HTML view as you would normally, and let Wicked take care of the hard stuff.

The speed of a single-page web application without having to write any JavaScript.

Official AWS Ruby gem for Amazon Simple Queue Service (Amazon SQS). This gem is part of the AWS SDK for Ruby.

The fastest JSON parser and object serializer.

This gem is used to get quickly started with the Shopify API

help to kill N+1 queries and unused eager loading.