Transforming your Tests with Kotlin

We know we should write tests, and we know that Kotlin gives us some nice features to use in our code, so how can we put these two together? There are some really great ways that Kotlin is being used in test writing, and we'll look at a number of them. This will include features such as higher order functions and escaping back-ticks and how they can make your tests more expressive. We'll also look at some testing libraries that take advantage of Kotlin's features. At the end of this talk you'll walk away with an understanding of how you can use Kotlin to make your tests more enjoyable.

Transcript

1. Transforming Your Tests With Kotlin Victoria Gonda
   victoriagonda.com
   @TTGonda
   

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2. Testing with Kotlin
   

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3. https://twitter.com/TTGonda/status/1123025116139544576
   

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4. Victoria Gonda
   • Android Engineer at Buffer
   • Author and Editor at RayWenderlich.com
   • Hedgehog and cat owner
   • she/her
   

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5. Kotlin features
   

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6. `Backticks`
   

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7. https://twitter.com/skentphd/status/1123035724788453377 https://twitter.com/jshvarts/status/1123362376840040448
   

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8. Without `Backticks`
   @Test
   fun whenDeleteIsCalled_onlyCorrespondingDataIsDeleted() {
   }
   

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9. `Backticks`
   @Test
   fun `deleteUpdates only deletes corresponding data`() {
   }
   

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10. `Backticks`
    java.lang.AssertionError: Assertion failed at
    package.Test.deleteUpdates only deletes corresponding data
    

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11. Higher order functions
    

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12. https://twitter.com/wakingrufus/status/
    1123053243800653825
    https://twitter.com/RBusarow/status/
    1123057633261441024
    https://twitter.com/jessewilson/status/
    1123055645824028672
    

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13. Higher order functions
    fun verifyLinkOpen(expectedUrl: String, openLink: () -> Unit) {
    Intents.init()
    try {
    openLink()
    intended(allOf(hasAction(ACTION_VIEW), hasData(expectedUrl)))
    } finally {
    Intents.release()
    }
    }
    

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14. Higher order functions
    verifyLinkOpen("https://buffer.com") {
    clickBufferButton()
    }
    

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15. Screen Robots
    

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16. Screen Robots
    class CalculatorScreenRobot : ScreenRobot() {
    fun verifyTipIsCorrect(tip: String): CalculatorScreenRobot {
    return checkViewHasText(R.id.textTip, tip)
    }
    fun inputCheckAmountAndSelectOkayButton(input: String):
    CalculatorScreenRobot {
    return enterTextIntoView(R.id.inputAmount, input)
    .clickOkOnView(R.id.buttonOkay)
    }
    }
    

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17. Screen Robots
    withRobot(CalculatorScreenRobot::class.java)
    .inputCheckAmountAndSelectOkayButton("11")
    .verifyTipIsCorrect("1.98")
    

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18. Screen Robots
    robot {
    inputCheckAmountAndSelectOkayButton("11")
    verifyTipIsCorrect("1.98")
    }
    

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19. Extension functions
    

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20. https://twitter.com/objcode/status/1123082385090908160
    

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21. Without Extension functions
    assert(contentViewModel.observeQueueState().value ==
    ContentState.Loading())
    

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22. Extension functions
    private fun ContentViewModel.hasState(state: ContentState) {
    assert(observeQueueState().value == state)
    }
    

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23. Extension functions
    contentViewModel.hasState(ContentState.Loading())
    

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24. Infix functions
    

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25. https://twitter.com/PreusslerBerlin/status/
    1123107023103696896
    https://twitter.com/jossiwolf/status/
    1123039773541707776
    

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26. Without Infix functions
    fun verifyTipIsCorrect(tip: String) {
    onView(withId(R.id.textTip))
    .check(matches(withText(tip)))
    }
    

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27. Infix functions
    infix fun Int.shouldHaveText(expected: String) {
    onView(withId(this))
    .check(matches(withText(expected)))
    }
    

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28. Infix functions
    fun verifyTipIsCorrect(tip: String) {
    R.id.textTip shouldHaveText tip
    }
    

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29. Combining multiple features
    inline fun > robot(block: T.() -> Unit) {
    T::class.java.newInstance().block()
    }
    robot {
    inputCheckAmountAndSelectOkayButton("11")
    verifyTipIsCorrect("1.98")
    }
    

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30. Data classes
    

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31. https://twitter.com/shekibobo/status/
    1123037412328988673
    https://twitter.com/tasomaniac/status/
    1123104225196683264
    

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32. Data classes
    data class UpdateData(
    var shareMode: ShareMode = ShareMode.ADD_TO_QUEUE,
    var media: MediaEntity? = null,
    var extraMedia: Array? = null,
    var retweet: RetweetEntity? = null,
    @Nullable var scheduledAt: Long? = null,
    var text: String = "",
    var facebookText: String = "",
    var profileIds: List? = null,
    var subProfileIds: List? = null,
    var sourceUrl: String? = null,
    var importId: String? = null,
    var shareDetails: ShareDetails? = null,
    var userChangedMedia: Boolean = false,
    var isEditing: Boolean = false,
    var editingProfile: ProfileEntity? = null,
    var networks: List? = null,
    var facebookTags: List? = null,
    var id: String? = "",
    var lastEditedDate: Long? = 0,
    var editingProfileTimezone: String? = null,
    val location: Location? = null,
    val commentEnabled: Boolean = false,
    val commentText: String? = null
    )
    

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33. Data classes
    UpdateData(null, null, emptyArray(), null, 0,
    "Hello World", "", emptyList(), emptyList(), null,
    "buffer.com", null, false, true,
    null, emptyList(), null, "", 0,
    null, null, false, "")
    

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34. Data classes
    UpdateData(text = "Hello World", sourceUrl = "buffer.com")
    

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35. Lazy property delegation
    

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36. https://twitter.com/POTUS404/status/1123210124108103680
    

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37. private val errorMessage by lazy { DataFactory.randomString() }
    

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38. Example
    https://youtu.be/wlb3lg5JocA
    

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39. Example
    https://youtu.be/wlb3lg5JocA
    

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40. Kotlin libraries
    

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41. Kakao
    

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42. https://twitter.com/erafn/status/1123067587125026816
    

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43. Kakao
    class SearchScreen : Screen() {
    val searchButton = KButton { withId(R.id.searchButton) }
    val snackbar = KView {
    withId(com.google.android.material.R.id.snackbar_text)
    }
    }
    

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44. Kakao
    screen {
    searchButton.click()
    snackbar.isDisplayed()
    }
    

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45. Spek
    

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46. Spek
    class ProfileSpec : Spek({
    given("twitter profile") {
    on("validate image count") {
    it("should be valid for four images") {
    }
    it("should fail for ten images") {
    }
    }
    }
    })
    

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47. Spek
    Spek:ProfileSpec:given twitter profile:on validate image count:it 

    should be valid for four images

    => java.lang.AssertionError: Expected , actual .
    

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48. Mockito-Kotlin
    

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49. https://twitter.com/Exallium/status/1123214566052323329
    

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50. Mockito
    val mockedUpdate = mock(Update::class.java)
    `when`(mockedUpdate.toString()).thenReturn("Update")
    

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51. Mockito-Kotlin
    val mockedUpdate = mock {
    on { toString() } doReturn "Update"
    }
    

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52. Kluent
    

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53. Kluent
    message shouldEqual "hello"
    message.shouldEqual("hello")
    message `should equal` "hello"
    

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54. Kluent
    invoking { read() } shouldThrow IOException::class
    

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55. Kluent
    Verify on mockedUpdate that mockedUpdate.toString() was called
    When calling stub.length itReturns 4
    

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56. Biscotti
    

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57. Biscotti
    verifyActivityLaunched(MainActivity::class.java.name) {
    onView(withId(R.id.button_faq))
    .perform(click())
    }
    

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58. https://vgonda.github.io/Talk-Resources/
    @TTGonda
    

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59. Thanks! Victoria Gonda
    victoriagonda.com
    @TTGonda
    

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