Shoulda Matchers provides RSpec- and Minitest-compatible one-liners that test common Rails functionality. These tests would otherwise be much longer, more complex, and error-prone.

This package provides a Ruby interface for secure random number generators.

This gem makes mathematical operations more precise in Ruby and integrates other mathematical standard libraries. Prior to Ruby 2.5, mathn was part of the Ruby standard library.

Spinach is a high-level BDD framework that leverages the expressive Gherkin language to help you define executable specifications of your code.

LazyObject is an object wrapper that forwards all calls to the reference object. This object is not created until the first method dispatch.

CiteProc is a citation processor interface and citation data API based on the CSL specifications. To actually process citations, a dedicated processor engine is required: a pure Ruby engine is available in the citeproc-ruby gem.

This gem provides parser dictionary data for AnyStyle.

Sorbet's runtime type checking component. Sorbet is a powerful type checker for Ruby.

TaskJuggler (tj3) is a project management tool for project planning and tracking using a domain specific language; projects are plain text files written using your favourite text editor. It includes reporting in HTML, CSV or iCalendar format and an email based status tracking system to send and receive time sheets from collaborators.

It covers the complete spectrum of project management tasks from the first idea to the completion of the project. It assists you during project scoping, resource assignment, cost and revenue planning, risk and communication management, status tracking and reporting.

crack provides really simple JSON and XML parsing, extracted from code in Merb and Rails.

rainbow provides a string presenter object to colorize strings by wrapping them in ANSI escape codes.

This gem is a library that provides trigonometric and transcendental functions for complex numbers. The functions in this module accept integers, floating-point numbers or complex numbers as arguments.

This package provides assorted command line tools that may be useful when working with Ruby code.

Sass is a CSS extension language. It extends CSS with features that don't exist yet like variables, nesting, mixins and inheritance.

This RSpec plugin allows you to use block_is_expected similarly to how you would use is_expected if a block was wrapping the subject.

Mocha is a mocking and stubbing library with JMock/SchMock syntax, which allows mocking and stubbing of methods on real (non-mock) classes.

This library provides contracts for Ruby. A contract describes the correct inputs and output for a method, and will raise an error if a incorrect value is found.

This package provides bindings for any kind of Ruby exceptions.

ChunkyPNG is a pure Ruby library that can read and write Portable Network Graphics (PNG) images without depending on an external image library. It tries to be memory efficient and reasonably fast. It has features such as:

• Decoding support for any image that the PNG standard allows. This includes all standard color modes, all bit depths, all transparency, and interlacing and filtering options.

• Encoding support for images of all color modes (true color, grayscale, and indexed) and transparency for all these color modes. The best color mode is chosen automatically, based on the amount of used colors.

• Read/write access to the image's pixels.

• Read/write access to all image metadata that is stored in chunks.

• Memory efficiency: fixnum are used, i.e. 4 or 8 bytes of memory per pixel, depending on the hardware).

• Performance: ChunkyPNG is reasonably fast for Ruby standards, by only using integer math and a highly optimized saving routine.

• Interoperability with RMagick.

ChunkyPNG is vulnerable to decompression bombs and can run out of memory when loading a specifically crafted PNG file. This is hard to fix in pure Ruby. Deal with untrusted images in a separate process, e.g., by using fork or a background processing library.

CharacterSet is a C-extended Ruby library to work with sets of Unicode code points. It can read and write these sets in various formats and implements the stdlib Set interface for them. It also offers an alternate paradigm of String processing which grants much better performance than Regexp and String methods from the stdlib where applicable. Many parts can be used independently, e.g.:

• CharacterSet::Character

• CharacterSet::Parser

• CharacterSet::Writer

• RangeCompressor

This package provides a native extension that can increase performance by about 25% compared to the pure Ruby WebSocket implementation.

The concurrent-ruby-edge gem includes concurrent-ruby features that are under active development and may change frequently. They are expected not to keep backward compatibility (there may also lack tests and documentation), although semantic versions are obeyed though. Features developed in concurrent-ruby-edge are expected to move to concurrent-ruby when final.

Ruby i18n is an internationalization and localization solution for Ruby programs. It features translation and localization, interpolation of values to translations, pluralization, customizable transliteration to ASCII, flexible defaults, bulk lookup, lambdas as translation data, custom key/scope separator, custom exception handlers, and an extensible architecture with a swappable backend.

Zeitwerk implements constant autoloading with Ruby semantics. Each gem and application may have their own independent autoloader, with its own configuration, inflector, and logger. Supports autoloading, reloading, and eager loading.