Introduction

Christopher Alexander famously observed that great environments share a pattern language – a network of proven responses to recurring forces. Chicago TDD Tools embodies the same philosophy for Rust testing. Instead of isolated utilities, the framework codifies high-leverage patterns that push teams toward dependable, behavior-focused tests and extendable architecture.

This cookbook distills those patterns. Each entry is written in Alexander's form so you can quickly scan the context, recognize the tension, and apply the solution. Read the patterns sequentially to see how they reinforce each other, or jump to the problem you have today.

The language is organized into three families:

1. Testing Patterns – maintainable, behavior-driven tests that fail fast and verify real outcomes.
2. Architecture Patterns – structural choices that keep the framework extensible and consistent.
3. Design Patterns – type-level techniques, zero-cost abstractions, and compile-time validation.

Combine these ingredients to build resilient Rust systems aligned with Chicago TDD principles: state-based testing, real collaborators, behavior verification, and the AAA pattern.