The document discusses Test-Driven Development (TDD) principles and techniques, emphasizing the importance of writing tests based on expectations rather than implementations. It outlines key steps in TDD, including asking about feature requirements, describing how features should work, and fulfilling those requirements through implementation. Additionally, it highlights the benefits of TDD, such as better code quality, faster development, and the importance of maintaining clean architecture.

1. Designing with Expectations, not
Implementations
Harshith Shetty

2. Test
● When to write tests?
● Does your test run fast?

3. Why TDD?

4. ● Ask
● Describe
● Fulfill
● Move on
Approach

5. Ask (what it’ll do)
● Expectations from the feature
● Clarity
● Documentation

6. Describe (how it’ll do)
● Interfaces of the feature
● Relationship between objects
● Flow of the feature
● Knowing when it’s done

7. Some Mocks:

8. Examples:

9. Fulfill (make it do)
● Implementation of feature
● Decoupled code
● Separation of business Logic from platform
● Faster feedback

11. Move on
*Test
*You

12. Move on
● Regression tests

13. Real life scenario
3 buttons x
7 states x
3 user types x
2 experiments
= 126 cases

15. *Refactoring
*New Features
*You
*Changing
Requirements
*Legacy code

17. 3 Laws of TDD
● You must write a failing test before you write any
production code.
- Robert C. Martin (Uncle Bob)
● You must not write more of a test than is sufficient to
fail, or fail to compile.
● You must not write more production code than is
sufficient to make the currently failing test pass.

18. Benefits
● Documented code
● Better code reviews
● Rewarding
● Refactor with Confidence
● Faster development cycles
● Less Debugging

19. Notes
● Always test the interfaces, Requirements are stable,
implementations are not.
● Follow a clean architecture.
● Practice. Practice. Practice. Make it a habit.
● Split the code, if tests become more.
● If not for product, do it for you.
● If not for you, do it for the next developer.

20. Examples:

21. Examples:

22. Examples:

23. ● @har5hit
● @ShaadiTech
Contact

24. ● “Ruby Midwest 2011 - Keynote: Architecture the Lost Years
by Robert Martin”
https://www.youtube.com/watch?v=WpkDN78P884
● “The Three Laws of TDD (Featuring Kotlin)”
https://www.youtube.com/watch?v=qkblc5WRn-U
● Growing Object-Oriented Software: Guided By Tests
by Steve Freeman
References