Quick is a behavior-driven development (BDD) testing framework for Swift and Objective-C, inspired by RSpec, Specta, and Ginkgo. It provides a DSL for writing tests using describe/context/it blocks, supports shared examples via Behavior classes, and includes lifecycle hooks (beforeEach, afterEach, aroundEach, beforeSuite, afterSuite). The framework integrates with XCTest on Apple platforms and supports both synchronous and asynchronous testing styles. Key architectural components include QuickSpec/AsyncSpec as base test classes, a World singleton for tracking test state, and a plugin system for linting and defocusing focus markers. Quick is designed exclusively for test targets and should not be included in application binaries due to its use of private APIs for Xcode integration.

Nimble is a matcher framework for Swift and Objective-C that provides a domain-specific language for writing expressive test assertions. It supports both synchronous and asynchronous testing through expect()/require() APIs and includes extensive matchers for equality, identity, truthiness, collections, and async operations. The architecture features a core matcher protocol, DSL layer for expectation creation, adapters for different testing frameworks (XCTest, Swift Testing), and utilities for source location tracking and string conversion. The framework is designed exclusively for test suites and should not be included in production binaries.