Guide to the jungle of testing frameworks

There are many tools, libraries and frameworks available for Android developers to test their applications. The jungle is huge and it's not easy to find the right ones. Some frameworks are good for unit testing, some are good for instrumentation testing, and some can be used for both. Some have great capabilities but annoying weaknesses. Some are good for testing UI, other allow you to make good mocks. We will look at many frameworks, the popular ones like Mockito, Robolectric, Espresso, and some other.
Presented at GDG DevFest Pilsen 2016.

Transcript

2. Unit Testing Experience on Android
4. Android apps are difficult to test
5. Types of Android tests
6. Types of Android tests Instrumentation tests Local unit tests
7. Android test code • project sources • ${module}/src/main/java • instrumentation tests • ${module}/src/androidTest/java • unit tests • ${module}/src/test/java • full Gradle and Android Studio support
9. • the essential piece of both instrumentation and unit tests • alone can be used only for pure Java • doesn’t provide any mocks or Android APIs
10. Instrumentation Tests
11. Instrumentation Tests • running on physical device or emulator • gradle connectedAndroidTest • ${module}/build/reports/androidTests/connected/ index.html
13. Instrumentation Tests Legacy instrumentation tests or Testing Support Library
14. Legacy Instrumentation Tests • JUnit3 • Tests extend from TestCase • AndroidTestCase • ActivityInstrumentationTestCase2 • ServiceTestCase • … deprecated since API level 24
15. Testing Support Library • JUnit4 compatible • AndroidJUnitRunner android { defaultConfig { testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" } } dependencies { androidTestCompile 'com.android.support.test:runner:0.5' }
16. Testing Support Library • JUnit test rules • AndroidTestRule • ServiceTestRule • DisableOnAndroidDebug • LogLogcatRule • … androidTestCompile 'com.android.support.test:rules:0.5'
18. • framework for functional UI tests • part of Android Testing Support Library androidTestCompile 'com.android.support.test.espresso:espresso-core:2.2.2'
19. @Test public void sayHello() { onView(withId(R.id.edit_text)) .perform(typeText(STRING_TO_BE_TYPED), closeSoftKeyboard()); onView(withText("Say hello!")) .perform(click()); String expectedText = "Hello, " + STRING_TO_BE_TYPED + "!"; onView(withId(R.id.textView)) .check(matches(withText(expectedText))); }
20. Problems • testing on device is not isolated • device state affects the result • e.g. screen on/off might affect test result onView(withId(R.id.my_view)) .check(matches(isDisplayed()));
21. Some annoyances android.support.test.espresso.NoActivityResumedException: No activities in stage RESUMED. Did you forget to launch the activity. (test.getActivity() or similar)?
22. Instrumentation tests are kinda SLOOOOOW
23. Unit Tests
24. Unit Tests • run on JVM • mockable android.jar • gradle test • ${module}/build/reports/tests/${variant}/index.html
25. ...
27. • Helps rarely • returns 0, false, null, … Method ... not mocked. android {
 testOptions {
 unitTests.returnDefaultValues = true }
 }
29. • mocking framework • easy to use • compatible with Android unit testing testCompile 'org.mockito:mockito-core:2.2.11'
30. • can be used also in instrumentation tests • needs dexmaker androidTestCompile 'org.mockito:mockito-core:2.2.11' androidTestCompile 'com.google.dexmaker:dexmaker:1.2' androidTestCompile 'com.google.dexmaker:dexmaker-mockito:1.2'
31. @RunWith(JUnit4.class) public class ContextManagerTest { @Mock Context mAppContext; @Before public void setUp() { MockitoAnnotations.initMocks(this); } @Test public void testWithContext() { … } }
32. @RunWith(MockitoJUnitRunner.class) public class ContextManagerTest { @Mock Context mAppContext; @Test public void testWithContext() { … } }
33. @RunWith(JUnit4.class) public class ContextManagerTest { @Test public void testWithContext() { Context appContext = mock(Context.class); Mockito.when(appContext.getPackageName()) .thenReturn(“com.example.app”); … } }
34. • Mockito.spy() • wrapping a real object • Mockito.verify() • verify that special condition are met • e.g. method called, method called twice, …
35. Limitations • final classes • opt-in incubating support in Mockito 2 • anonymous classes • primitive types • static methods
37. • functional testing framework • runs on JVM • at first, might be difficult to use • the ultimate mock of Android APIs • provides mocks of system managers • allows custom shadows
38. • possible to use for UI testing • better to use for business logic @RunWith(RobolectricTestRunner.class) public class MyTest { … }
39. • Robolectric • RuntimeEnvironment • Shadows • ShadowApplication • ShadowLooper
40. Potential problems • difficult to search for solutions • long history of bigger API changes • many obsolete posts
42. • Can mock static methods • Can be used together with Mockito
43. @RunWith(PowerMockRunner.class) @PrepareForTest(Static.class); PowerMockito.mockStatic(Static.class); Mockito.when(Static.staticMethod()) .thenReturn(value); PowerMockito.verifyStatic(Static.class);
45. • “matchers on steroids” • offers more complex checks assertThat(myClass, isInstanceOf(MainActivity.class)); assertThat(myManager.getValue(), isEqualTo(someValue)); assertThat(value, isIn(listOfValues)); assertThat(value, not(isIn(listOfValues)));
47. • cross-platform BDD framework • human-like test definitions testCompile ‘junit:junit:4.12' testCompile ‘info.cukes:cucumber-java:1.2.5' testCompile 'info.cukes:cucumber-junit:1.2.5'
48. • describe the desired behaviour Feature: CoffeeMaker
 
 Scenario: a few coffees
 Given I previously had 3 coffees
 When I add one coffee
 Then I had 4 coffees
49. • create the mapping public class CoffeeMakerDefs {
 CoffeeMaker mCoffeeMaker = new CoffeeMaker();
 
 
 
 
 }
50. • create the mapping public class CoffeeMakerDefs {
 CoffeeMaker mCoffeeMaker = new CoffeeMaker();
 
 @Given("^I previously had (\\d+) coffees$")
 public void hadCoffeesPreviously(int coffees) {
 mCoffeeMaker.setCoffeeCount(coffees);
 }
 
 
 }
51. • create the mapping public class CoffeeMakerDefs {
 CoffeeMaker mCoffeeMaker = new CoffeeMaker();
 
 @Given("^I previously had (\\d+) coffees$")
 public void hadCoffeesPreviously(int coffees) {
 mCoffeeMaker.setCoffeeCount(coffees);
 }
 
 @When("^I add one coffee$")
 public void addCoffee() {
 mCoffeeMaker.addCoffee();
 }
 
 
 }
52. • create the mapping public class CoffeeMakerDefs {
 CoffeeMaker mCoffeeMaker = new CoffeeMaker();
 
 @Given("^I previously had (\\d+) coffees$")
 public void hadCoffeesPreviously(int coffees) {
 mCoffeeMaker.setCoffeeCount(coffees);
 }
 
 @When("^I add one coffee$")
 public void addCoffee() {
 mCoffeeMaker.addCoffee();
 }
 
 @Then("^I had (\\d+) coffees$")
 public void hadCoffees(int coffees) {
 Assert.assertEquals(coffees, mCoffeeMaker.getCoffeeCount());
 }
 }
53. • place definition and mapping at the same paths! • ${module}/src/test/java/com/example/MyMapping.java • ${module}/src/test/resources/com/example/ MyDefinition.feature @RunWith(Cucumber.class)
 public class RunCucumberTest {
 }
54. Code Coverage
55. Code Coverage • instrumentation tests • JaCoCo • EMMA • obsolete • unit tests • JaCoCo
56. Instrumentation Tests & Code Coverage • has to be explicitly enabled • gradle createDebugCoverageReport • ${module}/build/reports/coverage/debug/index.html • ${module}/build/outputs/code-coverage/connected/$ {deviceName}-coverage.ec • doesn’t work on some devices!!! buildTypes {
 debug {
 testCoverageEnabled true
 } }
57. JaCoCo
58. JaCoCo • enabled by default for unit tests • gradle test • generates binary report in build/jacoco • ${module}/build/jacoco/testDebugUnitTest.exec • it’s necessary to create a JacocoReport task to obtain a readable report
61. Good tests
62. Good tests • run in any order • run in isolation • run consistently • run fast • are orthogonal
63. How to write testable apps?
64. Rules of thumb • prefer pure Java • abstract away from Android APIs • separate business logic and UI • don’t write business logic into activities and fragments • MVP, MVVM is a way to go • try avoid static and final • use dependency injection
65. Questions?