Introduction to JUnit and Robolectric

Resources:
Robolectric - http://robolectric.org/
Android Studio Gradle & Robolectric starter project - https://github.com/robolectric/deckard-gradle
Robolectric example projects - https://github.com/robolectric/robolectric-samples

Transcript

1. Android Unit Testing Intro to JUnit and Robolectric
2. Android Unit Testing Intro to JUnit and Robolectric But first, some thoughts on testing…
3. Executes & verifies a specific functionality Unit Test
4. What to test? YOUR code // don’t test framework
5. Why test? Check business rules Protect existing code Increase quality
6. Life and death Clients have complex business rules
7. Self defense Keep n00bs from messing shit up
8. Can’t test it? YOUR code is bad and YOU should feel bad
9. Can’t test it? YOUR code is bad and YOU should feel bad refactor
10. Why test? Check business rules Protect existing code Increase quality Cover our ass!
11. How do we test in Java?
12. JUnit Java unit testing framework
13. “test classes” public class MyClassTest {
 …
 } Separate test folder/packages Only used for testing
14. @Test
 public void testShouldPass() {
 boolean expected = true;
 boolean actual = true;
 
 assertEquals(expected, actual);
 } @Test annotation Assertion we are testing
15. Asserts compare expectation with reality
16. @Test
 public void depositShouldUpdateAccountBalance() {
 double startingBalance = 100.00;
 BankAccount bankAccount = new BankAccount(startingBalance);
 
 double newDeposit = 20.00;
 bankAccount.depositAmount(newDeposit);
 
 double expectedBalance = 120.00;
 
 assertEquals(expectedBalance, bankAccount.getBalance());
 }
17. Assertions assertEquals
 assertNotEquals
 assertTrue
 assertFalse
 assertNull
 assertNotNull
 assertThat
18. Annotations @Test
 @Before
 @After
 @Ignore
19. public class MyClassTest {
 
 private BankAccount bankAccount;
 
 @Before
 public void setup() {
 double startingBalance = 100.00;
 bankAccount = new BankAccount(startingBalance);
 }
 
 @Test
 public void depositShouldUpdateAccountBalance() {
 double newDeposit = 20.00;
 bankAccount.depositAmount(newDeposit);
 
 double expectedBalance = 120.00;
 
 assertEquals(expectedBalance, bankAccount.getBalance());
 }
 
 @Test
 public void withdrawalShouldUpdateAccountBalance() {
 double newWithdrawal = 20.00;
 bankAccount.withdrawalAmount(newWithdrawal);
 
 double expectedBalance = 80.00;
 
 assertEquals(expectedBalance, bankAccount.getBalance());
 }
 } Using @Before
20. Naming @Test
 public void multiplicationOfZeroShouldReturnZero() {
 …
 } public class NumberCruncherTest {
 …
 } add “Test” suffix to class name include “should” long names are cool
21. Command Line
 IDE (run configuration)
22. Execute on Java Virtual Machine Java tests
23. What about Android? one little problem…
24. Java source code Java Byte Code Java Byte Code ! Java VM Java
 Compiler Dalvik Executable ! Dalvik VM Java source code Java Byte Code Java 
 Compiler Dex
 Compiler Dalvik Byte Code
25. What about Android? oh yea one more little thing…
26. What the !#@$
27. What the Stub java.lang.RuntimeException: Stub!
28. “your unit tests should only test your code and not depend on any particular behavior of the Android platform” Google says:
29. Android Testing Framework by Google
30. Android Testing Framework by Google WACK Requires device or emulator Very slowwwww What about TDD Must build an .apk
32. #blessed
33. Run Android tests on JVM What does it do? Include Android classes in tests Tests are fast
34. How can this be? Rewrites Android class method bodies java.lang.RuntimeException: Stub!
35. but wait there’s more Maintains Views and Resources Provides Shadow Objects of Android classes
36. @RunWith(RobolectricTestRunner.class)
 public void MainActivityTest {
 
 @Test
 public void titleIsCorrect() {
 Activity activity = Robolectric.setupActivity(MainActivity.class);
 assertTrue(activity.getTitle().toString().equals(“Hello world”);
 }
 } Test runner Helper functions
37. @RunWith Tells JUnit to use Robolectric
38. /** * Calls the same lifecycle methods on the Activity called by 
 * Android the first time the Activity is created. * * @return Activity controller instance. */ public ActivityController<T> setup() { return create().start().postCreate(null).resume().visible(); } Calls lifecycle methods for you
39. @RunWith(RobolectricTestRunner.class) public class MyActivityTest { ! @Test public void clickingButton_shouldChangeResultsViewText() throws Exception { Activity activity = Robolectric.setupActivity(MyActivity.class); ! Button pressMeButton = (Button) activity.findViewById(R.id.press_me_button); TextView results = (TextView) activity.findViewById(R.id.results_text_view); ! pressMeButton.performClick(); String resultsText = results.getText().toString(); assertThat(resultsText, equalTo("Testing Android Rocks!")); } } Another example
40. Shadow Objects Maintains state of actual component Exposes private methods & fields
41. When would I use a shadow object? View state of private variable
42. When would I use a shadow object? View state of private variable Example: AlertDialog How can I test title and message are correct? getTitle() and getMessage() are private ShadowAlertDialog dialogShadow = shadowOf(alert);
 assertThat(dialogShadow.getTitle().toString().equals(“Dialog title”);
43. @Test public void shouldHaveALogo() throws Exception { ImageView pivotalLogo = (ImageView) activity.findViewById(R.id.pivotal_logo); ShadowImageView shadowPivotalLogo = Robolectric.shadowOf(pivotalLogo); assertThat(shadowPivotalLogo.resourceId, equalTo(R.drawable.pivotallabs_logo)); }
44. Parting thoughts
45. Robolectric is not perfect Best available solution Only supports up to SDK 18 Random test failures initializationError
46. When am I done testing? Never
47. When am I done testing? Never How confident are you?
48. Testing goals Test coverage > 60% ? Public methods all have tests? Is your ass covered?
49. Mocking Mockito & JMockIt Next time Dependency Injection Dagger
50. Resources Robolectric http://robolectric.org/ Example project for configuring Gradle & Robolectric https://github.com/robolectric/deckard-gradle Robolectric project samples https://github.com/robolectric/robolectric-samples