Test with confidence, code with clarity

Your home for mastering Test-Driven Development through real-world katas and expert guidance.

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Kata Catalog

Practice TDD with a curated set of real-world katas, each with clear requirements and test cases.

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Guides & References

Learn best practices, naming conventions, and advanced TDD techniques from industry experts.

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Interactive Learning

Discover the TDD Gears model and learn how to apply TDD principles in real-world scenarios.

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Industry Driven Insights

What years of real-world TDD have taught us

  • Reflection after each Red-Green-Refactor cycle is crucial for improvement
  • SOLID and DRY principles alone aren't enough for long-term test suite health
  • Tests should read like stories, revealing clear intent through domain concepts
  • Well-named, compact tests are more maintainable and encourage team contribution

TDD Gears

  • Low Gear: Build context and get started
  • Medium Gear: Enhance design and apply patterns
  • High Gear: Follow existing architectural patterns
  • Reverse Gear: Back up and try different approaches
TDD Gears

Science Based Reasoning

100x

Costlier to fix bugs in production vs. design time

Source: IBM System Sciences Institute

40-80%

Reduction in production bug density with TDD

Source: IEEE Software

20 min

Time to regain focus after interruption

Source: Fast Company

TDD isn't just about design—it's about code correctness. The human condition impacts our ability to write clean, correct code. When developers are interrupted to fix production bugs, they lose 40 minutes of productivity: 20 minutes to build context for the bug fix and another 20 to return to their original task.

TDD helps developers regain focus faster by reducing memory load. Without TDD, developers must carry all aspects of their work in their head, leading to significant disruption when interrupted.