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Unit Testing Android Applications
The document discusses effective unit testing strategies for Android, emphasizing the importance of automation, writing tests first, and utilizing various test doubles like mocks and stubs. It highlights the use of frameworks such as Mockito and Robolectric to facilitate testing while addressing common issues like slow tests and dependencies on specific platforms. The document concludes with recommendations for good testing practices and resources for further reading.
Unit Testing Android Applications
- 1. Tests, Stubs, Mocks Effective Unittesting for android
- 2. Goals of testautomation Improve quality Understand the SUT Reduce the risk Easy to run Easy to write Easy to maintain Subject Under Test
- 3. Principles in testautomation Write the test first. Each test should be: – Small and simple – Independent to other test – Repeatable – Self-checking Fully Automated First do “State verification” and then “Behavior Verification”.
- 4. Which part canbe automated?
- 5. System Under Test It may have Depended-on components Image From: xunit Test Patterns, G. Meszaros
- 6. What are wetalking about? Pattern: Test Double Also known as: Imposter Problem: How can we verify logic independently when code it depends on is unusable? How can we avoid Slow Tests? Solution: We replace a component on which the SUT depends with a "test- specific equivalent."
- 7. WHAT? Test Doubles: DummyObject: Temporary Object that does not influence the SUT Test Stub: Hand coded object used for testing Test Spy: Verification occurs after the test method has been called Mock Object: Expectations configured before calling tests Fake Object: Typically, it implements the same functionality as the real DOC but in a much simpler way, no expectation are configured.
- 8. Mock? Why? Mock- a simulated object that mimics the behavior of a real object in controlled ways.
- 9. Four phase testing ImageFrom: xunit Test Patterns, G. Meszaros
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- 11. Effective test automation After test generation by considering all paths and the features and organization specified, our test still may have these bad smells: – Slow Tests – Test Code Duplication – Obscure Tests – Buggy Tests
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- 13. Mockito, how todrink it? framework basics import static org.mockito.Mockito.*; //mock creation LinkedList mockedList = mock(LinkedList.class); //using mock object mockedList.add("one"); mockedList.clear(); //verification verify(mockedList).add("one"); verify(mockedList).clear(); Stub - Mockito can mock concrete classes, not only interfaces
- 14. Mockito, how todrink it? framework basics Return value thenReturn() when(mock.someMethod("some arg")).thenReturn("foo"); Stubbing voids requires doReturn() doReturn("bar").when(mock).foo();
- 15. What else touse PowerMock (private, final,static methods) Jmockit (constructors and static methods mocking) Hamcrest (library of matcher objects (also known as constraints or predicates) allowing 'match' rules to be defined declaratively)
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- 17. EXAMPLE: JUNIT +ROBOLECTRIC for Android Android unit testing is tricky: – android.jar only contains mocked out .class files which leads to java.lang.RuntimeException: Stub! TIPS: – Keep things simple by trying to make as many services as possible not dependent on the parts of the Android platform that are not compatible with a conventional JVM. – Robolectric to the rescue
- 18. Unit test dependingon Android api @RunWith(RobolectricTestRunner.class) public class PopularRoutesAdapterTest { private PopularRoutesAdapter adapter; @Before public void setUp() { adapter = new PopularRoutesAdapter( Robolectric.buildActivity(Activity.class).create().get(); } @Test public void testAddItem() { assertEquals(0, adapter.getCount()); adapter.addItem(new Route("Arnhem")); assertEquals(1, adapter.getCount()); } Special test runner coming with Robolectric Activity class is mocked by Robolectric
- 19. General rules toremember Mock it outside your code If you cannot test your code -> then probably you should change it ;) cause its badly written Test first Only one concrete class , mock the rest Only mock your neirest neighbour (Law of Demeter -> dont talk with strangers) Think ;) and then write
- 20. Robo-WTF Robolectric Has Java implementationsof class files for most of the Android API Enables true unittesting, being not dependent on any network, hardware, device or database Roboguice Guice for Robolectric Dependency Injection based in Google Guice Code bases DI instead of XML (like in Spring)
- 21. Deckard Combination of –Gradle / Maven – Robolectric – Junit Example adds – Roboguice – Mockito
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- 23. Developers Not WritingTests Symptoms: – No tests can be found when you ask to see the • unit tests for a task, • customer tests for a User Story, – Lack of clarity about what a user story or task really means Impact: – Lack of safety net – Lack of focus Possible Causes: – Hard to Test Code? – Not enough time? – Don’t have the skills? – Have been told not to? – Don’t see the value? Robolectric for unittesting Espresso for scenario-testing
- 24. Resources https://github.com/ddoa/dea-code- examples/android-deckard-unittest/ http://pages.cpsc.ucalgary.ca/~maurer/upload s/SENG515615F2007/XUnitTestPattern.ppt http://code.google.com/p/mockito/ https://docs.google.com/presentation/d/1J0W iFJI9wSkc3UMsNXYv8ixX5orjkYzduwyOalzEk jU/embed?hl=pl&size=l#slide=id.p5