Testing frameworks for Android

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Testing frameworks Pavel Shchahelski Android Developer Slimware

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Tests? • Take time • Adding code to code base • Slow down

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Write Tests • Rapid feedback on failures • Easier to ﬁx on early stage • Safety net • Free to refactor, clean up, optimize • Backbone of software

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@LargeTest @MediumTest @SmallTest Type of tests

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Android test code • project sources • ${module}/src/main/java

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Android test code • project sources • ${module}/src/main/java • instrumentation tests • ${module}/src/androidTest/java

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Android test code • project sources • ${module}/src/main/java • instrumentation tests • ${module}/src/androidTest/java • unit test • ${module}/src/test/java

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Unit Tests

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Unit Tests • Run on JVM • Modiﬁed android.jar • gradle test • ${module}/build/reports/tests/${variant}/index.html

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Unit Tests android { ... testOptions { unitTests.returnDefaultValues = true } }

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JUnit

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JUnit • Used to test pure java/kotlin • Does not provide any mocks or Android APIs • The main part of both unit and instrumentation tests

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class ExampleUnitTest { @Test fun addition_isCorrect() { assertEquals(4, 2 + 2) } } JUnit

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Assertions • assertEquals • assertNotEquals • assertTrue • assertFalse • assertNull • assertNotNull • assertThat

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Annotations • @BeforeClass • @Rule • @Before • @Test • @After • @AfterClass • @Ignore https://cdn-images-1.medium.com/max/1000/1*Lp8XW7Flz91G8GoISm9NKA.jpeg

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Annotations @RunWith(JUnit4::class) class ExampleUnitTest { private lateinit var myClass: MyClass private lateinit var map: MutableMap @Before fun setUp() { myClass = MyClass() map = mutableMapOf() } @Test fun addition_isCorrect() { assertEquals(4, 2 + 2) } @After fun tearDown() { map.clear() } }

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Runners @RunWith(JUnit4::class) class ExampleUnitTest 1. BlockJUnit4ClassRunner 2. GuiceJUnitRunner 3. MockitoJUnitRunner 4. SpringJUnit4ClassRunner 5. . . .

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http://www.vogella.com/tutorials/Mockito/article.html https://github.com/mockito/mockito

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Mockito • Very readable syntax • Annotation support • Large stackoverﬂow community • Most popular Java/Android mocking framework

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Mockito 1. ${project}/build.gradle    repositories { jcenter() } 2. ${module}/build.gradle  dependencies {   ...    testCompile "org.mockito:mockito-core:2.+"   }

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Mockito • Creating a mock • Verifying • Stubbing methods • Limitations • Capturing

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Mockito • Creating a mock • Verifying • Stubbing methods • Limitations • Capturing

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Creating a mock private lateinit var postExecution: PostExecutionThread @Before fun setUp() { postExecution = Mockito.mock(PostExecutionThread::class.java) } https://examples.javacodegeeks.com/core-java/mockito/mockito-initmocks-example/

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Test doubles • Dummy • Stub • Spy • Mock

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Test doubles • Dummy • Stub • Spy • Mock

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Dummy class Messenger(private val templateEngine: TemplateEngine, private val mailServer: MailServer) { fun sendMessage(client: Client, template: Template) { val msgContent: String = templateEngine.prepare(template, client) mailServer.send(client.getEmail(), msgContent) } } @Test fun testDummy(){ val template = mock(Template::class.java) sut.sendMessage(client, template) }

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Test doubles • Dummy • Stub • Spy • Mock

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Stub class Messenger(private val templateEngine: TemplateEngine, private val mailServer: MailServer) { fun sendMessage(client: Client, template: Template) { val msgContent: String = templateEngine.prepare(template, client) mailServer.send(client.getEmail(), msgContent) } } @Test fun testStub(){ val templateEngine = mock(TemplateEngine::class.java) val sut = Messenger(mailServer, templateEngine) `when`(templateEngine.prepare(template, client)) .thenReturn(MSG_CONTENT) sut.sendMessage(client, template) }

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Test doubles • Dummy • Stub • Spy • Mock

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Spy class Messenger(private val templateEngine: TemplateEngine, private val mailServer: MailServer) { fun sendMessage(client: Client, template: Template) { val msgContent: String = templateEngine.prepare(template, client) mailServer.send(client.getEmail(), msgContent) } } @Test fun testSpy(){ val mailServer = mock(MailServer::class.java) val sut = Messenger(mailServer, templateEngine) sut.sendMessage(client, template) verify(mailServer).send("some@email.com", msgContent) }

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Test doubles • Dummy • Stub • Spy • Mock

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Mockito • Creating a mock • Verifying • Stubbing methods • Limitations • Capturing

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Verifying private lateinit var sut: GetInstalledAppsUseCase private lateinit var repository: CachedAppRepository @Before fun setUp() { repository = mock() thread = mock() postExecution = mock() sut = GetInstalledAppsUseCase(repository, thread, postExecution) } @Test fun `test use case is built correctly`() { sut.buildUseCaseObservable(None) verify(repository).getInstalledApps() }

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Mockito • Creating a mock • Verifying • Stubbing methods • Limitations • Capturing

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Stubbing @Test fun stubMethod() { val user = User(webService, USER_ID, PASSWORD) `when`(webService.isOffline()).thenReturn(true) user.login() verify(webService, never()).login() }

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Stubbing @Test fun stubMethod() { val user = User(webService, USER_ID, PASSWORD) `when`(webService.isOffline()).thenReturn(true) user.login() verify(webService, never()).login() }

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Stubbing @Test fun stubMethod() { val user = User(webService, USER_ID, PASSWORD) `when`(webService.isOffline()).thenReturn(true) user.login() verify(webService, never()).login() } https://www.javacodegeeks.com/2013/02/testing-expected-exceptions-with-junit-rules.html

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Stubbing • Normal syntax    `when`(webService.isOffline()).thenReturn(true) • Alternative syntax    doReturn(true).`when`(webService).isOffline() • BDD    given(webService.isOffline()).willReturn(true) 

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Mockito • Creating a mock • Verifying • Stubbing methods • Limitations • Capturing

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Limitations • Unable to mock • static methods • private methods • hashcode() and equals()

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Mockito • Creating a mock • Verifying • Stubbing methods • Limitations • Capturing

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https://github.com/powermock/powermock

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PowerMock • Can mock static methods • Can be used together with Mockito

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PowerMock @RunWith(PowerMockRunner::class) @PrepareForTest(Static::class) class YourTestCase { @Test fun testMethodThatCallsStaticMethod() { // mock all the static methods in a class called "Static" PowerMockito.mockStatic(Static::class.java) // use Mockito to set up your expectation Mockito.`when`(Static.firstStaticMethod(param)).thenReturn(value) // execute your test classCallStaticMethodObj.execute() // Always use PowerMockito.verifyStatic(Class) first // to start verifying behavior PowerMockito.verifyStatic(Static::class.java, Mockito.times(2)) // IMPORTANT: Call the static method you want to verify Static.firstStaticMethod(param) } }

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Hamcrest https://code.google.com/archive/p/hamcrest/wikis/Tutorial.wiki

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What about Android?

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Android Testing Framework

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Android Testing Framework • AndroidJUnitRunner • JUnit4 Rules • Espresso • UiAutomator

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AndroidJUnitRunner • JUnit4 support • Collect tests • Execute tests • Report results

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JUnit4 Rules • ActivityTestRule • IntentsTestRule • ServiceTestRule • ProviderTestRule • GrantPermissionRule

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https://developer.android.com/training/testing/espresso/index.html

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Espresso 1. ${module}/build.gradle  dependencies {   ...    androidTestImplementation 'com.android.support.test:runner:1.0.1' androidTestImplementation ‘com.android.support.test.espresso:espresso-core:3.0.1'  } 2. ${module}/build.gradle  android.defaultConfig {     testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner" }

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Espresso @Test fun test(){ onView(ViewMatchers) .perform(ViewAction) .check(ViewAssertion) }

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View @Test fun test(){ onView(withId(R.id.action_bar)) .perform(click()) .check(matches(isDisplayed())) }

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View @RunWith(AndroidJUnit4::class) class LoginActivityTest { @Rule @JvmField val loginActivityRule = ActivityTestRule(LoginActivity::class.java) @Test fun shouldVerifyEmptyPassword(){ onView(withId(R.id.email)) .perform(typeText("Alex"), closeSoftKeyboard()) onView(withId(R.id.login)) .perform(click()) onView(withId(R.id.password)) .check(matches(withError(`is`("Please enter a password")))) } }

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View fun withError(expected: Matcher): Matcher { return object : TypeSafeMatcher() { override fun matchesSafely(item: View): Boolean { return if (item is TextInputLayout) { expected.matches(item.error.toString()) } else false } override fun describeTo(description: Description) { description.appendText("with error message: ") description.appendText(expected.toString()) } } }

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Lists @Test fun test(){ onData(ObjectMatcher) .DataOptions .perform(ViewAction) .check(ViewAssertion) }

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RecyclerView • actionOnHolderItem • actionOnItem • actionOnItemAtPosition • scrollTo • scrollToHolder • scrollToPosition

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RecyclerView @Test fun test(){ onView(withId(R.id.recycler_view)) .perform(actionOnItemAtPosition(3, click())) }

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Synchronization • Message Queue • AsyncTask • Idling Resources

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http://robolectric.org/

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Robolectric • Run Android tests on JVM • Tests are fast • Include Android classes in tests

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Robolectric ${module}/build.gradle  dependencies {   ...    testImplementation ‘org.robolectric:robolectric:3.6.1’ }

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Robolectric @RunWith(RobolectricTestRunner::class) class MainActivityTest { @Test fun testTitleColor(){ val activity = Robolectric.setupActivity(MainActivity::class) assertTrue(activity.getTitle().toString().equals("Main Activity")) } }

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Robolectric @RunWith(RobolectricTestRunner::class) /** * Calls the same lifecycle methods on the Activity called by Android the first time the Activity is created. * * @return Activity controller instance. */ public ActivityController setup() { return create().start().postCreate(null).resume().visible(); }

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Robolectric @RunWith(RobolectricTestRunner::class) class MyActivityTest { @Test @Throws(Exception::class) fun clickingButton_shouldChangeResultsViewText() { val activity = Robolectric.setupActivity(MyActivity::class.java) val button = activity.findViewById(R.id.button) as Button val results = activity.findViewById(R.id.results) as TextView button.performClick() assertThat(results.getText().toString()) .isEqualTo("Robolectric Rocks!") } }

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Resources • https://developer.android.com/training/testing/index.html • https://www.youtube.com/watch?v=pK7W5npkhho&feature=youtu.be • https://www.youtube.com/watch?v=AlxMGxs2QnM&feature=youtu.be • https://www.youtube.com/watch?v=DJDBl0vURD4 • https://dzone.com/articles/understanding-junits-runner • http://www.vogella.com/tutorials/AndroidTesting/article.html • http://myhexaville.com/2018/01/01/android-local-tests-robolectric/

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Resources • http://www.vogella.com/tutorials/Robolectric/article.html • http://www.vogella.com/tutorials/Mockito/article.html • https://www.linkedin.com/pulse/mockito-2x-over-powermock-migration-tips- tricks-top-ten-hazem-saleh/ • https://android.jlelse.eu/building-a-shazam-clone-part-5-discover-song-feature- building-android-apps-series-a70f7c3a9795 • https://android.jlelse.eu/animated-custom-view-driven-by-tests-5f082190acd6 • https://fernandocejas.com/2017/02/03/android-testing-with-kotlin/

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Resources • https://proandroiddev.com/testing-user-interface-of-android-app-with- architecture-components-data-binding-and-dagger-2-5d15c3779807 • https://academy.realm.io/posts/360-andev-2017-inaki-villar-advanced-expresso/ • https://www.philosophicalhacker.com/post/psa-dont-use-esprsso-idling- resources-like-this/ • https://android.jlelse.eu/helping-androiddev-to-mock-tests-in-kotlin- ab3be5204559#.8l72082k2 • https://dzone.com/articles/7-popular-unit-test-naming • https://www.youtube.com/watch?v=AlxMGxs2QnM&feature=youtu.be

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Resources • https://engineering.21buttons.com/mocking-kotlin-classes-with-mockito-the-fast- way-631824edd5ba • Growing Object-Oriented Software, Guided by Tests by Steve Freeman, Nat Pryce (Book) • Tomek Kaczanowski - Practical Unit Testing with JUnit and Mockito (Book) • XUnit Test Patterns Refactoring Test Code (Book)