The document discusses best practices for automated Android testing, including testing utilities, Android components, the UI, and expected user behavior. It recommends using support libraries like Instrumentation, Android JUnit Runner, Espresso, and UIAutomator for testing. Espresso allows testing UI interactions within an app, while UIAutomator can test interactions between apps and the system. Tests should be decoupled and use stubs for dependencies that can't be controlled. Everything that could cause errors, like getter/setters, should be tested.

1. A guide to automated
Android testing
by @darrillaga

2. Challenges

3. What to test
1. Utilities
2. Android components
3. UI
4. Expected user behavior

4. What to test
1. Utilities
2. Android components
3. UI
4. Expected user behavior

5. Utilities
Utilities are every piece of code, both pure java
and Android-dependant, that are used as tools
in the development process.

6. What to test
1. Utilities
2. Android components
3. UI
4. Expected user behavior

7. Android components
1. Activities
2. Fragments
3. Services
These are the most common components.

8. What to test
1. Utilities
2. Android components
3. UI
4. Expected user behavior

9. UI
UI specific behavior and custom views.

10. What to test
1. Utilities
2. Android components
3. UI
4. Expected user behavior

11. Expected user behavior
Functional testing on our activities, based on
expected behavior.

12. How to test
1. Using support libraries
2. Stub code we can’t control while testing
3. Decoupled code
4. Testing everything that could be error-prone

13. How to test
1. Using support libraries
2. Stub code we can’t control while testing
3. Decoupled code
4. Testing everything that could be error-prone

14. Using support libraries
1. Instrumentation
2. Android JUnit Runner
3. Espresso
4. UIAutomator

15. Using support libraries
1. Instrumentation
2. Android JUnit Runner
3. Espresso
4. UIAutomator

16. Instrumentation
This framework monitors all of the interaction
between the Android system and the
application.
Android testing libraries are built on top of the
Instrumentation framework.

17. Using support libraries
1. Instrumentation
2. Android JUnit Runner
3. Espresso
4. UIAutomator

18. AndroidJUnitRunner
JUnit test runner that lets you run JUnit 3 or JUnit 4-style
test classes on Android devices, including those using the
Espresso and UI Automator testing frameworks.
The test runner handles loading your test package and the
app under test to a device, running your tests, and
reporting test results.

19. Using support libraries
1. Instrumentation
2. Android JUnit Runner
3. Espresso
4. UIAutomator

20. Espresso
APIs for writing UI tests to simulate user interactions within
a single target app.
Provides automatic sync of test actions with the app’s UI.

21. Using support libraries
1. Instrumentation
2. Android JUnit Runner
3. Espresso
4. UIAutomator

22. UI Automator
This framework provides a set of APIs to build UI tests that
perform interactions on user apps and system apps.
The UI Automator APIs allows you to perform operations
such as opening the Settings menu or the app launcher in a
test device.

23. How to test
1. Using support libraries
2. Stub code we can’t control while testing
3. Decoupled code
4. Testing everything that could be error-prone

24. Stub code we can’t control with testing
1. Robospice
2. Card reader
3. Thermal printer SDK
4. Bluetooth

25. How to test
1. Using support libraries
2. Stub code we can’t control while testing
3. Decoupled code
4. Testing everything that could be error-prone

26. Decoupled code
1. Android components only in charge of
lifecycle
2. Layer for business logic
3. Layer modeling views
4. Create utilities for code that can be unit
tested

27. How to test
1. Using support libraries
2. Stub code we can’t control while testing
3. Decoupled code
4. Testing everything that could be error-prone

28. Testing everything that could be error-prone
1. Do not test getter/setters
2. Test code created by us
3. Do not test third-party code (stub it or let it
be)

29. Wrapping up

30. Android
Components
Utilities
Android system
UI
Stubs

31. Android
Components
Utilities
Android system
UI
Stubs

32. Android
Components
Utilities
Android system
UI
Stubs
Unit testing
● jUnit
● Instrumentation

33. jUnit
Unit test
private EmailValidator subject = new EmailValidator();
@Test
public void doesNotValidateWithInvalidEmail() {
String email = "invalidEmail";
assertThat(subject.isValid(email), is(false));
}

34. jUnit + Instrumentation
Unit test
// This component uses the Android framework out of our control so we need to use instrumentation to provide a context
private CurrentUserSessionService subject = new CurrentUserSessionService(InstrumentationRegistry.
getTargetContext());
@Test
public void isCurrentSessionPresentReturnsTrueWithCurrentUser() {
subject.saveUserSession(buildUserSession());
assertThat(subject.isCurrentSessionPresent(), is(true));
}
private UserSession buildUserSession() {
// creates stub user session instance
}

35. Android
Components
Utilities
Android system
UI
Stubs

36. Android
Components
Utilities
Android system
UI
Stubs
Using manual or library-assisted dependency injection to
switch dependencies for stubs when testing

37. Android
Components
Utilities
Android system
UI
Stubs

38. Android
Components
Utilities
Android system
UI
Stubs
Espresso to manipulate and unit-
test views in an isolated Activity

39. Android
Components
Utilities
Android system
UI
Stubs

40. Android
Components
Utilities
Android system
UI
Stubs
UI automator
Functional test of interactions
between the app and the Android
system

41. Android
Components
Utilities
Android system
UI
Stubs
Functional testing
● Espresso
● Espresso Intents
● Instrumentation
● Stubs

42. Functional test
@Test
public void unauthorizedUserLogin() {
registerInvalidCredentialsLoginRequest();
setUserAndPassword();
clickOnSignIn();
Context context = InstrumentationRegistry.getTargetContext();
String errorMessage = context.getString(R.string.InvalidCredentialsError);
onView(allOf(withText(errorMessage), withParent(withId(R.id.errors_wrapper)))).
check(matches(isDisplayed()));
}
LoginActivity - Android components + Stubs + Espresso + Instrumentation

43. Stub
LoginActivity
@Rule
public SpicedTestRule<LoginActivity> mTestRule = new SpicedTestRule<>(LoginActivity.class);
private void registerInvalidCredentialsLoginRequest() {
Charset utf8 = Charset.forName("utf-8");
mTestRule.registerResponseFor(
LoginRequest.class,
new HttpClientErrorException(
HttpStatus.BAD_REQUEST,
"error",
FixturesLoader.getFixtures().get("AuthenticatePasswordInvalidCredentialsErrorResponse"),
utf8
)
);
}

44. Stub
LoginActivity
@Rule
public SpicedTestRule<LoginActivity> mTestRule = new SpicedTestRule<>(LoginActivity.class);
private void registerInvalidCredentialsLoginRequest() {
Charset utf8 = Charset.forName("utf-8");
mTestRule.registerResponseFor(
LoginRequest.class,
new HttpClientErrorException(
HttpStatus.BAD_REQUEST,
"error",
FixturesLoader.getFixtures().get("AuthenticatePasswordInvalidCredentialsErrorResponse"),
utf8
)
);
}

45. Functional test
@Test
public void unauthorizedUserLogin() {
registerInvalidCredentialsLoginRequest();
setUserAndPassword();
clickOnSignIn();
Context context = InstrumentationRegistry.getTargetContext();
String errorMessage = context.getString(R.string.InvalidCredentialsError);
onView(allOf(withText(errorMessage), withParent(withId(R.id.errors_wrapper)))).
check(matches(isDisplayed()));
}
LoginActivity

46. Functional test
@Test
public void unauthorizedUserLogin() {
registerInvalidCredentialsLoginRequest();
setUserAndPassword();
clickOnSignIn();
Context context = InstrumentationRegistry.getTargetContext();
String errorMessage = context.getString(R.string.InvalidCredentialsError);
onView(allOf(withText(errorMessage), withParent(withId(R.id.errors_wrapper)))).
check(matches(isDisplayed()));
}
LoginActivity

47. Espresso Usage
private UserSession mUserSession = CurrentUserSessionTestHelper.buildUserSession();
private void setUserAndPassword() {
onView(ViewMatchers.withId(R.id.email)).perform(typeText(mUserSession.getEmail()));
onView(withId(R.id.password)).perform(typeText("password"));
}
private void clickOnSignIn() {
onView(withId(R.id.action_login)).perform(click());
}
LoginActivity

48. Instrumentation
@Test
public void unauthorizedUserLogin() {
registerInvalidCredentialsLoginRequest();
setUserAndPassword();
clickOnSignIn();
Context context = InstrumentationRegistry.getTargetContext();
String errorMessage = context.getString(R.string.InvalidCredentialsError);
onView(allOf(withText(errorMessage), withParent(withId(R.id.errors_wrapper)))).
check(matches(isDisplayed()));
}
LoginActivity

49. Instrumentation
@Test
public void unauthorizedUserLogin() {
registerInvalidCredentialsLoginRequest();
setUserAndPassword();
clickOnSignIn();
Context context = InstrumentationRegistry.getTargetContext();
String errorMessage = context.getString(R.string.InvalidCredentialsError);
onView(allOf(withText(errorMessage), withParent(withId(R.id.errors_wrapper)))).
check(matches(isDisplayed()));
}
LoginActivity

50. Espresso usage
@Test
public void unauthorizedUserLogin() {
registerInvalidCredentialsLoginRequest();
setUserAndPassword();
clickOnSignIn();
Context context = InstrumentationRegistry.getTargetContext();
String errorMessage = context.getString(R.string.InvalidCredentialsError);
onView(allOf(withText(errorMessage), withParent(withId(R.id.errors_wrapper)))).
check(matches(isDisplayed()));
}
LoginActivity

51. Espresso usage
onView(
allOf(
withText(errorMessage),
withParent(
withId(R.id.errors_wrapper)
)
)
).check(
matches(
isDisplayed()
)
);
LoginActivity

52. Espresso usage
onView(
allOf(
withText(errorMessage),
withParent(
withId(R.id.errors_wrapper)
)
)
).check(
matches(
isDisplayed()
)
);
LoginActivity

53. Espresso usage
onView(
allOf(
withText(errorMessage),
withParent(
withId(R.id.errors_wrapper)
)
)
).check(
matches(
isDisplayed()
)
);
LoginActivity

54. Espresso usage
onView(
allOf(
withText(errorMessage),
withParent(
withId(R.id.errors_wrapper)
)
)
).check(
matches(
isDisplayed()
)
);
LoginActivity

55. Espresso usage
onView(
allOf(
withText(errorMessage),
withParent(
withId(R.id.errors_wrapper)
)
)
).check(
matches(
isDisplayed()
)
);
LoginActivity

56. Espresso usage
onView(
allOf(
withText(errorMessage),
withParent(
withId(R.id.errors_wrapper)
)
)
).check(
matches(
isDisplayed()
)
);
LoginActivity

57. Espresso usage
onView(
allOf(
withText(errorMessage),
withParent(
withId(R.id.errors_wrapper)
)
)
).check(
matches(
isDisplayed()
)
);
LoginActivity

58. Espresso usage
onView(
allOf(
withText(errorMessage),
withParent(
withId(R.id.errors_wrapper)
)
)
).check(
matches(
isDisplayed()
)
);
LoginActivity

59. Intents
Functional test - Landing Activity
@Test
public void testOnEnterAction() {
Intent result = new Intent();
intending(hasComponent(hasClassName(equalTo(LoginActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_OK, result)
);
intending(hasComponent(hasClassName(equalTo(HomeActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_CANCELED, null)
);
clickOn(R.id.action_enter);
intended(hasComponent(hasClassName(equalTo(HomeActivity.class.getName()))));
}

60. Intents
Functional test - Landing Activity
@Test
public void testOnEnterAction() {
Intent result = new Intent();
intending(hasComponent(hasClassName(equalTo(LoginActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_OK, result)
);
intending(hasComponent(hasClassName(equalTo(HomeActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_CANCELED, null)
);
clickOn(R.id.action_enter);
intended(hasComponent(hasClassName(equalTo(HomeActivity.class.getName()))));
}

61. Intents
Functional test - Landing Activity
@Test
public void testOnEnterAction() {
Intent result = new Intent();
intending(hasComponent(hasClassName(equalTo(LoginActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_OK, result)
);
intending(hasComponent(hasClassName(equalTo(HomeActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_CANCELED, null)
);
clickOn(R.id.action_enter);
intended(hasComponent(hasClassName(equalTo(HomeActivity.class.getName()))));
}

62. Intents
Functional test - Landing Activity
@Test
public void testOnEnterAction() {
Intent result = new Intent();
intending(hasComponent(hasClassName(equalTo(LoginActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_OK, result)
);
intending(hasComponent(hasClassName(equalTo(HomeActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_CANCELED, null)
);
clickOn(R.id.action_enter);
intended(hasComponent(hasClassName(equalTo(HomeActivity.class.getName()))));
}

63. Intents
Functional test - Landing Activity
@Test
public void testOnEnterAction() {
Intent result = new Intent();
intending(hasComponent(hasClassName(equalTo(LoginActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_OK, result)
);
intending(hasComponent(hasClassName(equalTo(HomeActivity.class.getName())))).
respondWith(
new Instrumentation.ActivityResult(Activity.RESULT_CANCELED, null)
);
clickOn(R.id.action_enter);
intended(hasComponent(hasClassName(equalTo(HomeActivity.class.getName()))));
}

64. Android
Components
Utilities
Android system
UI
Stubs

65. Android
Components
Utilities
Android system
UI
Stubs
Unit testing
● jUnit
● Instrumentation

66. Android
Components
Utilities
Android system
UI
Stubs
Using manual or library-assisted dependency injection to
switch dependencies for stubs when testing
Unit testing
● jUnit
● Instrumentation

67. Android
Components
Utilities
Android system
UI
Stubs
Espresso to manipulate and unit-
test views in an isolated Activity
Using manual or library-assisted dependency injection to
switch dependencies for stubs when testing
Unit testing
● jUnit
● Instrumentation

68. Android
Components
Utilities
Android system
UI
Stubs
Espresso to manipulate and unit-
test views in an isolated Activity
UI automator
Functional test of interactions
between the app and the Android
system
Using manual or library-assisted dependency injection to
switch dependencies for stubs when testing
Unit testing
● jUnit
● Instrumentation

69. Android
Components
Utilities
Android system
UI
Stubs
Espresso to manipulate and unit-
test views in an isolated Activity
Functional testing
● Espresso
● Espresso Intents
● Instrumentation
● Stubs
UI automator
Functional test of interactions
between the app and the Android
system
Using manual or library-assisted dependency injection to
switch dependencies for stubs when testing
Unit testing
● jUnit
● Instrumentation

70. ...then 2 + 2 = 4 so...
We can test on Android!

71. References
https://developer.android.com/training/testing.html
http://developer.android.com/reference/android/app/Instrumentation.html
https://developer.android.com/tools/testing-support-library/index.html

72. Thanks to
Ariel, Gian, Juanma, Michel
@moove_it

73. Questions?