This document discusses test-driven development (TDD) in Android and provides examples of how to apply TDD principles. It explains what TDD is and the typical "red-green-refactor" process. It also notes some challenges of TDD in Android, such as difficulty mocking Android components. The document advocates separating an app into layers (e.g. view, presenter, model) to enable individual testing and provides a demo of how to structure an app with login functionality into testable layers. Finally, it outlines some benefits of TDD like faster feedback, better design, and confidence during refactoring.

1. W e l c o m e
TDD INANDROID
Let's see how you can apply TDD in the Android ecosystem

2. What is TDD
2
Write a Failing Test
Make the (failing)
Test PassRefactor

3. Example
3

4. Example
4

5. Example
5

6. Example
6

7. Example
7

8. Why TDD is challenge in Android?
8
• Doing every work at one place making it difficult to test another
• Mocking of android components is difficult

9. Separation of Concerns
9
• Define the concerns of different components in Codebase
• Create different layers as per their responsibility
• Test each layer separately

10. Demo screen
10
Invalid Login
Valid Login

11. Layers in Demo Screen
11
View Logic is separated from Data Models
Presenter acts as communicator between Business logic and View logic.
View Actions
(Login Activity)
Login
Presenter
Login Model
Click Login
Check User
Existence
Validate UserUpdate UI
Accordingly

12. Testing mechanisms in Android
12
• Unit Test
๏Junit
๏Mockito
• Integration Test
๏Espresso
๏Junit

13. What we achieve from TDD
13
• Faster Feedback (Testing at each layer)
• Encourage Good Design (Smaller modules/ Reusability)
• Easily Extensible and Maintainable Code (adding new code is easy/ tweaking
existing code)
• Confidence while Refactoring (TDD provides its best results when code is
constantly improved)

14. THANK YOU
For questions or suggestions:
Prateek Jain: prateekj@thoughtworks.com