leejunkim

Test-Driven Development (TDD)

2 min read

Tdd

Test-Driven Development (TDD) is a software development methodology where test code is written first, followed by the actual implementation code that satisfies those tests.

  • Usually used when
    • Developing new features
    • Improving legacy code

Process

  • diagram
  1. Understand Requirements: Clearly comprehend the feature request or bug report.
  2. Write Failing Test (Red): Based on the understanding, write a unit test. Since no implementation code exists yet, this test will initially fail. (Note: If hot-reloading is configured, tests may run automatically here.)
  3. Implement Minimum Code (Green): Write just enough production code to make the failing test pass. Run all tests; if all pass, proceed. If not, repeat this step.
  4. Refactor (Clean Code): Once functionality is confirmed, refactor and improve the code (e.g., remove duplication, improve naming, optimize structure). All tests must still pass.
  5. Repeat: Go back to step 1 for the next feature or bug, and repeat (Rinse, lather, and repeat) the cycle.

Advantages of TDD

  • Significantly improves code quality.
  • Encourages feature decomposition into small units, enabling a divide-and-conquer approach for development.
    • TDD를 잘하면 정말 잘게잘게 작은 단위로 나울 수 있음
  • Clear understanding and definition of requirements.
  • Enables stable refactoring.
  • Minimizes regression errors.
  • Ensures high test coverage.

Need to know BDD (Behavior-driven development)

  • Uses the Given-When-Then structure to write tests.
  • Helps in designing clear, behavior-focused test cases.
  • Often used to complement TDD by making tests readable and aligned with business behavior.

Disadvantages

  • high learning curve lol (u need to be good at using tools like Mockito)
    • Can get very deep and complex in practice.
    • Applying it in real-world projects is hard unless all team members have strong TDD knowledge.
  • 어느 시점에서 어떤 테스트 객체가 필요할지 미리 생각하고 코드 작성 > 경험 기반. 어려움!

Spring

  • Spring Boot Support:

    • Spring is designed with testable code in mind from the start.

    • Offers built-in support for various testing libraries, making TDD easier to apply.

  • Spring’s POJO-based design

Graph View

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