On Unit Test, TDD and BDD

Table of content

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.

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