Overview
Want to master Test-Driven Development through practical examples? This by-example guide teaches TDD through annotated code examples organized by complexity level.
What Is TDD By-Example Learning?
TDD by-example learning is a code-first approach where you learn through practical implementations of the Red-Green-Refactor cycle rather than narrative explanations. Each example shows:
- Failing tests first - Red phase demonstrating test-first thinking
- Minimal implementation - Green phase making tests pass with simplest code
- Refactoring - Improving design while keeping tests green
- Production patterns - Proven approaches from industry leaders
This approach is ideal for developers who want to master test-first development through hands-on practice.
Learning Path
The TDD by-example tutorial guides you through examples organized into three progressive levels, from basic unit testing to enterprise-scale TDD implementations.
Coverage Philosophy
This by-example guide provides practical coverage of TDD through annotated examples. The focus is on implementing TDD workflows, not just theory.
What’s Covered
- TDD fundamentals - Red-Green-Refactor cycle, test-first thinking
- Testing patterns - Assertions, fixtures, test organization
- Test doubles - Mocks, stubs, fakes, spies
- Advanced techniques - Asynchronous testing, property-based testing, mutation testing
- Production patterns - TDD with databases, web apps, microservices
- Legacy code - Characterization tests, refactoring strategies
- Enterprise TDD - Test architecture, scaling patterns, performance
What’s NOT Covered
- BDD and acceptance testing (see BDD tutorial for stakeholder collaboration)
- Manual testing techniques (see testing fundamentals)
- Framework documentation beyond common patterns
Prerequisites
- Programming experience in at least one language (Java, JavaScript, Python, Go, or similar)
- Basic understanding of functions, classes, and control flow
- Familiarity with testing concepts (assertions, test runners)
Structure of Each Example
Every example follows a consistent format:
- Brief Explanation: What TDD concept the example demonstrates
- Test Code (Red): Failing test showing requirements
- Implementation (Green): Minimal code to pass the test
- Refactored Version: Improved design preserving behavior
- Key Takeaway: The core TDD principle to retain
This structure provides the complete TDD cycle in every example, reinforcing the rhythm of test-first development.