On Unit Test, TDD and BDD

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TDD vs BDD

Video: TDD or BDD When It Comes To Automated Testing?

This great video of David Farley discusses the benefits and challenges of automated testing, and compares two approaches: test-driven development (TDD) and behavior-driven development (BDD). It argues that BDD is a more effective starting point for improving automated testing in most cases, and explains how to implement it using a domain-specific language and a four-layer approach.

The classic TDD cycle (Red → Green → Refactor):

flowchart LR
    R["🔴 Red<br/>Escribir un test que falla"] --> G["🟢 Green<br/>Código mínimo para que pase"]
    G --> RF["🔵 Refactor<br/>Mejorar el diseño sin romper tests"]
    RF -->|siguiente requisito| R

Highlights:

1. The problem of automated testing
   • Most people prefer software with good automated tests
   • Manual testing is slow, expensive, and unpredictable
   • The question is how to automate testing effectively
2. The value of test-driven development
   • TDD gives fast and clear feedback on the design of the system
   • TDD produces lots of decoupled (if there are correctly written) tests that can run frequently
   • TDD is a valuable tool for individual developers
3. The difficulty of test-driven development
   • TDD is hard to retrofit to existing code that is not well designed
   • TDD requires refactoring skills and discipline
   • TDD is easier to adopt for new code than for old code
4. The alternative of behavior-driven development
   • BDD is easier to retrofit to existing code of any technology
   • BDD focuses on what the system does, not how it does it
   • BDD involves creating a domain-specific language (DSL) to script scenarios
5. The process of behavior-driven development
   • Start by learning how to determine the releasability of the system
   • Use acceptance test driven development to build the DSL
   • Start with a simple scenario and grow the DSL as needed
   • Use the four-layer approach to separate concerns and avoid coupling

1. The benefits of behavior-driven development
   • BDD can replace manual testing with automated tests quickly
   • BDD can run the tests all the time and give faster feedback
   • BDD can increase the determinism and control of the system

References

• 10 Pines videos — Academia 10 Pines
• 10 Pines Diseño a la Gorra — Academia 10 Pines
• Test-Driven Development — Wikipedia
• TestDrivenDevelopment — Martin Fowler
• The Cycles of TDD — Robert C. Martin
• ¿Por qué hacer TDD? — Robert C. Martin (YouTube)

Notas relacionadas

• Gherkin and Automation
• BDD with Cucumber for JAVA