Currently, Fandy is the mobile apps tech lead works for OLX Indonesia and has been working on both Android and iOS since Cupcake and iOS 2.x respectively. As a tech lead he is responsible for delivering software into production safely and quickly in a sustainable way. *** This slide was shared at Tech in Asia Product Development Conference 2017 (PDC'17) on 9-10 August 2017. Get more insightful updates from TIA by subscribing techin.asia/updateselalu

1. Best Practice:
Unit Testing in
Mobile AppsIndonesia
Jakarta, July 2017
Fandy Gotama

2. 2
What To Do Before Writing Unit Test?
- Refactor your code,● You have legacy code?, Refactor it
● For a new project, use clean architecture approaches
● Convince yourself and your team, be consistent!
● Convince your BOSS!!, or should I?

3. 3
● Do Test Review instead of Code Review
● Understanding their intent
● Communication
Change Your Team Behaviour

4. 4
@Test
public void testGenerateDeviceToken() throws NoSuchAlgorithmException {
String ANY_DEVICE_ID = "123";
Generator generator = new Generator();
String token = generator.generateOAuthDeviceToken(ANY_DEVICE_ID);
Assert.assertEquals(“0bde9a580f199bd6856cc578", token);
}

5. 5
@Test
public void testCategoryTableCreatedSuccessfully() {
mDatabaseHelper =
new CategorySQLiteDatabaseHelper(
RuntimeEnvironment.application, DB_NAME, DB_VERSION);
SQLiteDatabase db = mDatabaseHelper.getReadableDatabase();
Cursor cursor = db.rawQuery(
"SELECT * FROM sqlite_master " +
"WHERE type='table' " +
"AND name = '" + Category.TABLE_NAME +"'", null);
assertEquals(1, cursor.getCount());
}

6. 6
Unit testing is a software development process in which the
smallest testable parts of an application, called units, are
individually and independently scrutinized for proper
operation. Unit testing can be done manually but is often
automated.
http://searchsoftwarequality.techtarget.com/definition/unit-testing
What is Unit Test?

7. 7
● Trustworthy
● Maintainable
● Readable
Best Practice - Writing Good Unit Test
http://osherove.com/blog/2012/9/17/readable-maintainable-trustworthy-unit
-tests-in-java.html

8. 8
@Test
public void testTransformApiResponseToModel() {
DataResponse response = mockResponse();
DataMapper mapper = new DataMapper();
for (CategoryResponse category : response.results) {
CategoryModel model = mapper.transform(category);
Assert.assertEquals(category.id, model.id);
}
}

9. 9
@Test
public void testProductIsExpired() {
long tomorrowInMillis = System.currentTimeMillis() + 86410000;
boolean isExpired = Product.checkExpiration(tomorrowInMillis);
Assert.assertEquals(true, isExpired);
}

10. 10
● Test driven
● Avoid logic in test
Trustworthy

11. 11
@Test
public void testTransformWithDefaultParamValueForPriceAndCondition() {
RequestModel requestModel = mockRequestWithEmptyCondition();
DataRequest request = mMapper.transform(requestModel);
Assert.assertEquals("bekas", request.params.get("condition"));
Assert.assertEquals("[price, 0]", request.params.get("price").toString());
}

12. 12
● Do not test private / protected methods
● Do not run test from another test
● Test one thing only
● Test can be run in any order
Maintainable

13. 13
@Test
public void testCalculateTotalAmount() throws Exception {
double anyPrice = 10000;
Calculation spyCalculation = spy(new Calculation());
Checkout checkout = new Checkout();
checkout.runCalculation(anyPrice, spyCalculation);
verify(spyCalculation).calculateDiscount();
verify(spyCalculation).addTax();
verify(spyCalculation).addShippingPrice();
verify(spyCalculation).updateAmount();
Assert.assertEquals(15000, checkout.getAmount());
}

14. 14
● Avoid testing internal works if it’s not important
● Only “verify” if that’s the only way to test your code
Maintainable

15. 15
@Test
public void testGetAge() {
int age = 24;
Permission permission = new Permission();
boolean isHavePermissionToEnter = permission.checkAge(age);
Assert.assertEquals(true, isHavePermissionToEnter);
}

16. 16
● Unit Test class name
● No magic variable
● Structure
Readable

17. 17
Building Unit Test on Mobile Apps

18. 18
public class MessagePresenter {
private final EmailService mService = new EmailService();
public void sendMessage(Context context, String message, String receiver) {
mService.send(message, receiver);
((MessageActivity) context).showLoading();
}
}

19. 19
public class MessagePresenter {
private final MessageServiceInterface mService;
private final View mView;
public MessagePresenter(MessageServiceInterface service, View view) {
mView = view;
mService = service;
}
public void sendMessage(String message, String receiver) {
mService.send(message, receiver);
mView.showLoading();
}
public interface View {
void showLoading();
}
}

20. 20
● Dependency Injection
● Loosely coupled
● Do not abuse static class
● Single responsibility principle
Building Unit Test on Mobile Apps

21. 21
DEMO
https://github.com/CommunityShareCode/UnitTesting

22. 22
Thank You

23. 23
● http://artofunittesting.com/java/
● http://www.journaldev.com/2394/java-dependency-injection
-design-pattern-example-tutorial
● http://blog.stevensanderson.com/2009/08/24/writing-great-
unit-tests-best-and-worst-practises/
● http://osherove.com/blog/2012/9/17/readable-maintainable-
trustworthy-unit-tests-in-java.html
● http://searchsoftwarequality.techtarget.com/definition/unit-t
esting
● https://blog.pragmatists.com/test-doubles-fakes-mocks-and
-stubs-1a7491dfa3da