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Aung Kyaw Paing
Senior Consultant @ thoughtworks | GDE Android
aungkyawpaing.dev
State of Junit 5 in
Android
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1997
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“JUnit was born on a flight from Zurich to
the 1997 OOPSLA in Atlanta. Kent was
flying with Erich Gamma, and what else
were two geeks to do on a long flight but
program?”
- Martin Fowler
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In fact, the original SUnit framework only has only
three small classes and twelve methods!
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“Never in the field of software
development have so many
owed so much to so few lines of
code”
- Martin Fowler
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2006
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Junit 4
- Annotations were introduced
- Method name no longer require you to start with “test” prefix
- Runners are introduced
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2016
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No content
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Runners
- Can only have one single runner for each test class
- You can’t have Parameterized test if you’re using other class runner like
AndroidTestRunner
- We want to separate runner, reporting and so on into different interfaces
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Execution model
- Requires all test to be known prior to execution
- Prevent dynamic creation of test cases during execution
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Toolchain
- IDEs and build tools are tightly coupled to JUnit internals
- Some tools use reflection to access internal APIs
- In short, JUnit 4 was not made to be extensible across multiple tools
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The vision
- Decouple test execution and reporting from test definition and provisioning
- Rethinking JUnit’s extensibility
- Make use of Java 8 features
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2017
JUnit 5 become stable
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What’s in JUnit 5
for me?
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Cleaner Reporting
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Kotlin Friendly
@Test
fun `should return invalid when text is empty`() {
...
}
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Multiple Assertions
Assertions.assertAll(
"Assertions subset of variable",
{ Assertions.assertEquals(actual.name, "Vincent")},
{ Assertions.assertEquals(actual.age, 28)},
{ Assertions.assertTrue(actual.isSpeaker)},
)
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Asserting Exceptions
val exception = assertThrows(
IOException::class.java
) {
functionThatThrow()
}
assertEquals(exception.message, "Error reading file")
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Assumptions
@Test
fun shouldGetFromDatabase() {
// Abort test if watch is not connected
Assumptions.assumeTrue(isConnectedToWearOS()))
// Execute test
}
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Inner Tests
class ProfileScreenTest {
@InnerTest
@DisplayName("when user is logged in")
inner class WhenUserLoggedInTests {
// ... test functions
}
@InnerTest
@DisplayName("when user is logged out")
inner class WhenUserLoggedOutTests {
// ... test functions
}
}
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Tagging
@Test
@Tag("Fast")
fun fastTestThatCanRunLocally()
@Test
@Tag("Slow")
fun slowTestThatWeRunOnCI()
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Tagging
task slowTest(type: Test) {
useJUnitPlatform {
includeTags 'slow'
}
}
// .gradlew slowTest
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Conditional tests
@Test
@EnabledOnOs({OS.MAC})
fun shouldRunOnlyOnMac() {
// ...
}
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Repeated tests
@RepeatedTest(value = 3, failureThreshold = 1)
fun flakyTests() {
// ...
}
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Parameterized tests
@ParameterizedTest
@ValueSource(
strings = ["", "abcd", "abc213"]
)
fun validateShouldReturnFalse(input: String) {
Assertions.assertFalse(validatePhoneNumber(input))
}
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Dynamic Tests
@TestFactory
fun apiContractTests(): List {
val apiDataFile : List = readAssetDir("api_tests")
apiDataFile.map { metadata ->
dynamicTest("API Test: ${metadata.endpoint}") {
// PING API
}
}
}
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JUnit 4 Backwards
compatibility
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class JUnit4Test {
@Before
fun setUp() { }
@After
fun tearDown() {}
@Test
fun test() {
Assert.assertEquals(true, true)
}
}
Similar structures
class JUnit5Test {
@BeforeEach
fun setUp() { }
@AfterEach
fun tearDown() {}
@Test
fun test() {
Assertions.assertEquals(true, true)
}
}
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@get:Rule
val composeTestRule = createComposeRule()
Rule —> Extensions
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Rule —> Extensions
@JvmField
@RegisterExtension
val extension = createComposeExtension()
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implementation
("org.junit.vintage:junit-vintage-engine")
Or just run Junit4!
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JUnit 5 on Android
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JUnit 5 on Android
- Google has no plan to officially support for Junit 5 as it will require a lot of resources
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JUnit 5 on Android
- Google has no plan to officially support for Junit 5 as it will require a lot of resources
- However we have community maintained plugin!
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plugins {
id("de.mannodermaus.android-junit5") version "1.11.2.0"
}
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plugins {
id("de.mannodermaus.android-junit5") version "1.11.2.0"
}
dependencies {
// (Required) Writing and executing Unit Tests on the JUnit Platform
testImplementation("org.junit.jupiter:junit-jupiter-api:5.11.2")
testRuntimeOnly("org.junit.jupiter:junit-jupiter-engine:5.11.2")
// (Optional) If you need "Parameterized Tests"
testImplementation("org.junit.jupiter:junit-jupiter-params:5.11.2")
// (Optional) If you also have JUnit 4-based tests
testImplementation("junit:junit:4.13.2")
testRuntimeOnly("org.junit.vintage:junit-vintage-engine:5.11.2")
}
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Instrumentation Tests
dependencies {
androidTestImplementation("org.junit.jupiter:junit-jupiter-api:5.11.2")
}
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Instrumentation Tests
class MyActivityTest {
@JvmField
@RegisterExtension
val scenarioExtension = ActivityScenarioExtension.launch()
@Test
fun myTest() {
val scenario = scenarioExtension.scenario
// Do something with the scenario here...
}
}
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Compose Tests
dependencies {
androidTestImplementation("de.mannodermaus.junit5:android-test-compose")
}
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Compose Tests
class ComposeTest {
@JvmField
@RegisterExtension
val extension = createComposeExtension()
@Test
fun composeTest() = extension.use {
setContent {
Text("Hello")
}
onNodeWithText("Hello").assertIsDisplayed()
}
}
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Roboletric Android JUnit4
- No official support yet (#3477)
- Is part of Google Summer of Code 2024 (Pitch Deck)
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Roboletric Android JUnit4
- No official support yet (#3477)
- Is part of Google Summer of Code 2024 (Pitch Deck)
- But we have a community plugin!
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Roboletric
plugins {
id("tech.apter.junit5.jupiter.robolectric-extension-gradle-plugin") version "0.8.0"
}
@ExtendWith(RobolectricExtension::class)
class RobolectricTest {
@Test
fun `JUnit5 with robolectric`() {
assertNotNull(RuntimeEnvironment.getApplication())
}
}
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Gradle Managed Device
Gradle Managed Device is the recommended way to run instrumentation tests as
it interacts with actual system API and it’s fast unlike running on actual emulators
or real devices. It is also scalable with Firebase Test Lab!
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testOptions {
managedDevices {
localDevices {
create("pixel") {
// Use device profiles you typically see in Android Studio.
device = "Pixel 2"
// Use only API levels 27 and higher.
apiLevel = 30
// To include Google services, use "google".
systemImageSource = "aosp"
}
}
}
}
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Unit Tests
Features Supported?
Instrumentation
Compose
Dagger Hilt
HiltAndroidRule has no equivalent extension as it requires
annotating with HiltAndroidTest to generate code
Robolectric Limited support
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My Recommendations
Unit Tests
Instrumentation Tests
UI Tests
E2E
Junit 5
Junit 5 running on
Gradle Managed
Device
Maestro, Appium
etc
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So what can you do?
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What can I do?
- +1 in the issue tracker and voice out if you have any
https://issuetracker.google.com/issues/127100532
- Thumbs up on Robolectric open issue
https://github.com/robolectric/robolectric/issues/3477
- Star android-junit5 library
https://github.com/mannodermaus/android-junit5
- Start using Junit5 in your app
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Aung Kyaw Paing
Senior Consultant @ thoughtworks | GDE Android
aungkyawpaing.dev
State of Junit 5 in
Android