My experiences on Unit Testing in the Android environment. I hope they are useful to you too. A brief tour about how to make Android Studio run your unit tests (logical and instrumentation) and how to start creating tests for your app.

1. 7 Stages of Unit
Testing in Android
Jorge D. Ortiz Fuentes
@jdortiz
#7SUnitTest

2. A POWWAU
production
#7SUnitTest

3. #7SUnitTest
Daring as a fool
★ Speaking from the shoulders of giants.
Look up here!
★ This is not UnitTesting 101, but
complementary to it

4. 1.

5. Shock & Disbelief

6. But my code is
always awesome!

7. #7SUnitTest
Unit Tests
★ Prove correctness of different aspects of the
public interface.
• Prove instead of intuition
• Define contract and assumptions
• Document the code
• Easier refactoring or change
★ Reusable code = code + tests

8. #7SUnitTest
Use Unit Testing
Incrementally
★ You don’t have to write every unit test
★ Start with the classes that take care of the
logic
• If mixed apply SOLID
★ The easier entry point are bugs

9. 2.

10. Denial

11. C’mon, it takes
ages to write
tests!

12. Time writing tests <
Time debugging

13. #7SUnitTest
Good & Bad News
★ Most things are already available in Android Studio
★ Projects are created with
• test package
• ApplicationTest class
★ It requires some tweaking
★ Google docs are for Eclipse
• modules instead of projects
• different UI…

14. OTS functionality
JUnit
AssertTestCase
AndroidTestCase
TestSuite
ApplicationTestCase
InstrumentationTes
tCase
ActivityInstrumenta
tionTestCase2
junit.framework

15. Run from IDE
Run in
(V)Device

16. 3.

17. Anger

18. How do I write
those f***ing
tests?

19. #7SUnitTest
Types of Unit Tests
★ Test return value
★ Test state
★ Test behavior

20. public class TaskTests extends TestCase {
final static String TASK_NAME = "First task";
final static String TASK_DONE_STRING = "First task:
Done";
final static String TASK_NOT_DONE_STRING = "First
task: NOT done";
Task mTask;
@Override
public void setUp() throws Exception { super.setUp();
mTask = new Task(); }
@Override
public void tearDown() throws Exception
{ super.tearDown();
mTask = null; }
public void testDoneStatusIsDisplayedProperly()
throws Exception {
mTask.setName(TASK_NAME);
mTask.setDone(true);
String taskString = mTask.toString();
assertEquals("String must be "taskname: Done"",
TASK_DONE_STRING, taskString);
}
public void testNotDoneStatusIsDisplayedProperly()
throws Exception {
mTask.setName(TASK_NAME);
mTask.setDone(false);
assertEquals("String must be "taskname: NOT done
"", TASK_NOT_DONE_STRING, mTask.toString()); } }
Example
public class Task {
private String mName;
private Boolean mDone;
public String getName() { return
mName; }
public void setName(String name)
{ mName = name; }
}
public Boolean getDone() { return
mDone; }
public void setDone(Boolean done) {
mDone = done;
}
@Override
public String toString() {
return mName + ": " +
(mDone?"Done":"NOT done");
}
}

21. public class ModelAndLogicTestSuite
extends TestSuite {
public static Test suite() {
return new
TestSuiteBuilder(ModelAndLogicTestS
uite.class)
.includePackages(“c
om.powwau.app.interactor”,
“com.powwau.app.data”)
.build();
}
public ModelAndLogicTestSuite()
{
super();
}
}
Running more than one
TestCase
public class FullTestSuite
extends TestSuite {
public static Test suite() {
return new
TestSuiteBuilder(FullTestSuite.cl
ass)
.includeAllPackag
esUnderHere()
.build();
}
public FullTestSuite() {
super();
}
}

22. Instrumentation Tests
public class MainActivityTest extends ActivityInstrumentationTestCase2<MainActivity> {
Activity mActivity;
public MainActivityUnitTest() {
super(MainActivity.class);
}
@Override
public void setUp() throws Exception {
super.setUp();
mActivity = getActivity();
}
public void testHelloIsDisplayed() throws Exception {
onView(withText(“Hello world!")).check(ViewAssertions.matches(isDisplayed()));
}
public void testSalutationChangesWithButtonClick() throws Exception {
onView(withText("Touch Me")).perform(click());
onView(withText("Bye bye,
Moon!”)).check(ViewAssertions.matches(isDisplayed()));
}
}

23. 4.

24. Bargain

25. Ok, I’ll write
some tests, but
make my life
simpler

26. #7SUnitTest
Dependency Injection
★ Control behavior of the dependencies
• Constructor
• Method overwriting
• Property injection:Lazy instantiation
★ Or use a DI framework: Dagger 2

27. Dependency Injection
for Poor Developers
public void preserveUserName(String name)
{
SharedPreferences prefs =
getPreferences(“appPrefs”,
Context.MODE_PRIVATE);
SharedPreferences.Editor editor =
prefs.edit();
editor.putString(USER_NAME_KEY, name);
editor.commit();
}

28. Dependency Injection
for Poor Developers
public void preserveUserName(String name) {
SharedPreferences prefs = getAppPrefs();
SharedPreferences.Editor editor = prefs.edit();
editor.putString(USER_NAME_KEY, name);
editor.commit();
}
SharedPreferences getAppPrefs() {
if (mAppPrefs == null) {
mAppPrefs = getPreferences(“appPrefs”,
Context.MODE_PRIVATE);
}
return mAppPrefs;
}

29. DataRepo dataRepoMock = mock(DataRepo.class);
when(dataRepoMock.existsObjWithId(23)).thenReturn(
true);
verify(dataRepoMock).deleteObjWithId(23);
Simulating and Testing
Behavior
★ Stubs & Mocks
• Both are fake objects
• Stubs provide desired responses to the SUT
• Mocks also expect certain behaviors

30. 5.

31. Guilt

32. But this ain’t
state of the art

33. #7SUnitTest
Problems so far
★ Tests run in (v)device: slow
★ Unreliable behavior:
• Command line
• Integration with mocking

34. 6.

35. Depression

36. My tests are
never good
enough!

37. #7SUnitTest
Use JUnit 4
★ Don’t extend TestCase
★ Don’t start with test (@Test instead)
★ @Before & @After instead of setUp and
tearDown. Also for the class
★ @ignore
★ Exceptions & timeouts (@Test params)
★ @Theory & @DataPoints

38. Gradle config
sourceSets {
test.setRoot(“src/test”)
}
dependencies {
testCompile 'junit:junit:4.12'
testCompile 'org.mockito:mockito-core:1.9.5'
androidTestCompile 'junit:junit:4.12'
androidTestCompile 'org.mockito:mockito-
core:1.9.5'
}

39. How to Use JUnit 4

40. #7SUnitTest
CLI-aware Also
★ ./gradlew check
• lint
• test
★ Open app/build/reports/tests/debug/
index.html

41. 7.

42. Acceptance &
Hope

43. No tests, no fun

44. #7SUnitTest
Evolve
★ Clean Architecture
★ TDD
★ Functional tests :monkeyrunner
★ CI (Jenkins)

45. Thank
you!

46. @jdortiz
#7SUnitTest