The document outlines best practices for unit testing within the Model-View-ViewModel (MVVM) architecture, particularly focusing on unit testing for models, view models, and views. It highlights the use of dependency injection and tools like Koin, Mockito, and Robolectric for facilitating tests. The presentation provides implementation details and emphasizes not testing generated code while ensuring expected outcomes from interactions and model changes.

1. Unit Tests Your
Views
Jorge D. Ortiz-Fuentes
@jdortiz

2. A Canonical
Examples
production
@jdortiz

3. @jdortiz
Agenda
★ Overview
★ Implementation details
★ I write tests
★ We write tests

4. Architecture

5. MVVM

6. MVVM
View
Model
ModelView
Events & Info Operations
Changes Changes

7. Architecture Components
View
Model
Room
Activity +
Fragments
Events & Info Operations
LiveData LiveData

8. Unit Testing

9. Testing Pyramid
Acceptance test
Integration tests
Unit tests
We are here

10. Unit Testing: Model
View
Model
Room
Activity +
Fragments
Events & Info Operations
LiveData LiveData

11. @jdortiz
Testing the Model
★ Use the defined operations -> Assertion on
results
★ Connect observe changes
★ Don’t test generated code!

12. Unit Testing: ViewModel
View
Model
Room
Activity +
Fragments
Events & Info Operations
LiveData LiveData

13. @jdortiz
Testing the ViewModel
★ Use mock as model
★ Input
• Invoke methods of the view model (used to
communicate events)
• Notify of changes in the model
★ Output: Check if
✦ The state of the view model is the expected one
✦ It invokes expected operations in the model

14. Unit Testing: View
View
Model
Room
Activity +
Fragments
Events & Info Operations
LiveData LiveData

15. @jdortiz
Testing the View
★ Inputs
• Changes in the properties of the view model
• User interacting with the views
★ Outputs
• The view changes as expected
• It tells the viewModel about the corresponding
events

16. Implementation
Details

17. @jdortiz
Dependency Injection
★ Koin
★ Very simple to use
★ For testing:
• Provide module with mocks
• override = true
• Use AutoCloseKoinTest

18. @jdortiz
Interacting with the
Views
★ Robolectric (4.0)
• Runner: (AndroidJUnit4:
androidx.test.ext:junit)
• Java 9 for testing Android Q
• Use Config sdk for Java 8
• Espresso actions and matchers
• Runs on JVM

19. Remember mockito-
kotlin configuration

20. Let’s write some
tests!

21. http://bit.ly/
droidconuk19

22. Thank
you!

23. @jdortiz
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24. @jdortiz
#AdvArchMobile