An introduction Effective Snapshot Testing on Android

Talk on Snapshot testing at Droidcon Berlin 2021 & Droidcon London 2021
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UI tests are a powerful tool to detect regression bugs. However, they are tedious to write and run very slow. But they are not the only tool we got to test the UI:
snapshot tests are some specific type of UI tests, that are not only easier to write but also run much faster than standard UI tests. They even help detect visual regression bugs that Espresso/UiAutomator tests cannot. Indeed, they are more widely used than UI tests by big companies such as Airbnb, with ≈ 30.000 snapshot tests, and Uber, with thousand of snapshot tests vs. a handful of UI tests, among others.

While there are plenty of resources about writing UI tests on Android, the same doesn't exist for snapshot tests. There is no guidance.

So, what is actually snapshot testing? how do you write a valuable snapshot test? what are the best practices? what are the pitfalls you have to take into account?

If you want to know how to get the most out of snapshot testing, come and join this tech talk. You will learn:
- what is snapshot testing and how your app can benefit from it
- how to decide what to snapshot test
- how to write your first meaningful snapshot test
- tips and tricks for better snapshot testing and what pitfalls to avoid
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Repo with code examples:
https://github.com/sergio-sastre/Road-To-Effective-Snapshot-Testing

Transcript

1. EFFECTIVE SNAPSHOT TESTING
   ON ANDROID
   BY SERGIO SASTRE
   AN INTRODUCTION TO
   

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2. WHAT
   Snapshot testing
   is
   

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3. Special type of UI tests
   take a screenshot of it,
   compare it to its reference
   we inflate a view,
   where
   and
   

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4. Snapshot tests Ui tests
   thousand handful
   Source: "Building Mobile Apps at scale - 39 Engineering Challenges"
   

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5. Snapshot tests Ui tests
   thousand handful
   ≈ 1 600 ≈ 500
   Source: "Building Mobile Apps at scale - 39 Engineering Challenges"
   

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6. Snapshot tests Ui tests
   thousand handful
   ≈ 1 600 ≈ 500
   ≈ 2 300 ≈ 20
   Source: "Building Mobile Apps at scale - 39 Engineering Challenges"
   

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7. Snapshot tests Ui tests
   thousand handful
   ≈ 1 600 ≈ 500
   ≈ 2 300 ≈ 20
   ≈ 30 000 ?
   Source: "Building Mobile Apps at scale - 39 Engineering Challenges"
   

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8. Ui tests
   Snapshot tests
   Icons made by “Freepik" from "Flaticon"
   writing speed
   

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9. Ui tests
   Snapshot tests
   Icons made by “Freepik" from "Flaticon"
   writing speed
   

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10. Ui tests
    Snapshot tests
    5-
    10
    sec
    Icons made by “Freepik" from "Flaticon"
    writing speed
    

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11. Ui tests
    Snapshot tests
    5-
    10
    sec
    Icons made by “Freepik" from "Flaticon"
    writing speed
    

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12. Ui tests
    Snapshot tests
    5-
    10
    sec
    1
    sec
    <
    Icons made by “Freepik" from "Flaticon"
    writing speed
    

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13. VS
    Snapshot
    

    tests
    User interface
    
    
    tests
    

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14. Snapshot
    

    tests
    User interface
    
    
    tests VS
    

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15. Snapshot
    

    tests
    User interface
    
    
    tests
    +
    

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16. Snapshot
    

    tests
    User interface
    
    
    tests
    +
    (interaction)
    WHAT
    

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17. Snapshot
    

    tests
    User interface
    
    
    tests
    +
    (interaction)
    WHAT HOW
    (visuals)
    

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18. MOTIVATION
    Snapshot test
    to
    

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19. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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20. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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21. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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22. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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23. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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24. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    which will expand till the end of the line and …
    

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25. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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26. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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27. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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28. Unexpected changes from library updates
    Spacing, styling, themes…
    Layout correctness
    Long text
    View overlapping
    Languages (RTL)
    System font size (HUGE)
    1
    2
    3
    visual bugs
    

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29. Example
    

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30. Layout validation
    

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31. Layout validation
    

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32. Settings Display Font size
    System font size
    >
    >
    

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33. Example
    

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34. Example
    

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35. Font Size
    Largest
    
    
    6,16%
    Small
    
    
    8,06%
    Large
    
    
    14,22%
    Default
    
    
    71,56%
    TT
    Source: Android app with 80 000 monthly active users
    

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36. Font Size
    Small
    
    
    8,06%
    Default
    
    
    71,56%
    TT
    20, 38 %
    Large + Largest
    Source: Android app with 80 000 monthly active users
    

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37. Do not trust Layout validation
    BUT
    Manual validation is hard
    

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38. 1
    Snapshot tests
    Use
    2
    Automate hard configs
    Catch regression bugs
    

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39. WORKS
    HOW
    Snapshot testing
    

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40. record
    AND
    verify
    

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41. write
    test
    CI
    

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42. record
    CI
    

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43. =
    CI
    

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44. CI
    new
    
    PR
    +
    

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45. approve
    CI
    

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46. merge
    CI
    

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47. CI
    new
    PR
    verify
    

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48. CI
    new
    PR
    

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49. CI
    new
    PR
    

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50. CI
    new
    PR
    

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51. CI
    new
    PR
    verify
    

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52. CI
    new
    PR
    

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53. CI
    new
    PR
    

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54. CI
    new
    PR
    

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55. CI
    Intentional change
    forgot to
    
    
    record
    regression
    
    
    bug
    YES
    NO
    

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56. CI
    Emulator config matters
    D1
    DN
    .
    .
    .
    

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57. CI
    Emulator config matters
    =
    D1
    DN
    =
    .
    .
    .
    =
    OR
    

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58. CI
    Emulator config matters
    D1
    =
    .
    .
    .
    DN
    =
    =
    OR
    

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59. CI
    Emulator config matters
    D1
    DN
    .
    .
    .
    =
    =
    

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60. CI
    Emulator config matters
    =
    D1
    =
    =
    .
    .
    .
    DN
    OR
    

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61. CI
    Emulator config matters
    =
    D1
    =
    =
    .
    .
    .
    DN
    OR
    

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62. 1
    2
    More complex than
    
    
    standard testing
    Same emulator config
    
    
    everywhere
    process
    Snapshot testing
    

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63. How to
    Snapshot test
    EFFECTIVELY
    

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64. Example
    

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65. Example
    

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66. Dealing with asynchronicity
    Choosing test-worthy screen states
    More views, more prone to flakiness
    1
    2
    3
    snapshot testing
    full screen
    

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67. Dealing with asynchronicity
    Choosing test-worthy screen states
    More views, more prone to flakiness
    1
    2
    3
    snapshot testing
    full screen
    

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68. Dealing with asynchronicity
    Choosing test-worthy screen states
    More views, more prone to flakiness
    1
    2
    3
    snapshot testing
    full screen
    

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69. Dealing with asynchronicity
    Choosing test-worthy screen states
    More views, more prone to flakiness
    1
    2
    3
    snapshot testing
    full screen
    

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70. Dealing with asynchronicity
    Choosing test-worthy screen states
    More views, more prone to flakiness
    1
    2
    3
    snapshot testing
    full screen
    

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71. start small & simple
    Header
    Training View
    Text
    view
    to memorise
    1
    split into smaller testable views
    

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72. Header
    Training View
    Text
    view
    to memorise
    start small & simple
    1
    what to test
    

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73. Header
    Training View
    Text
    view
    to memorise
    start small & simple
    1
    what to test
    

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74. A
    B
    start small & simple
    1
    Identifying view states
    

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75. A
    B
    start small & simple
    1
    Identifying view states
    

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76. aim to break the layout
    2
    Identifying unhappy paths
    

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77. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    

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78. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    words to train for all 7 languages
    

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79. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    words to train for all 7 languages
    huge system font size
    

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80. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    words to train for all 7 languages
    huge system font size
    narrow screen
    

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81. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    words to train for all 7 languages
    huge system font size
    narrow screen
    

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82. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    words to train for all 7 languages
    huge system font size
    narrow screen
    trainingInfo =

    TrainingItem
    (
    
    trainingByLang = wordsToTrainPerLang(999_999)
    ,
    
    activeLangs = Language.values().toSet(
    )
    
    ),
    TrainingTestItem(
    fontSize = FontScale.HUGE,
    viewWidth = ViewWidth.NARROW
    fun withWordsToTrainUnhappyPath() =
    )

    )
    Mock Data
    

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83. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    words to train for all 7 languages
    huge system font size
    narrow screen
    trainingInfo =

    TrainingItem
    (
    
    trainingByLang = wordsToTrainPerLang(999_999)
    ,
    
    activeLangs = Language.values().toSet(
    )
    
    ),
    TrainingTestItem(
    fontSize = FontScale.HUGE,
    viewWidth = ViewWidth.NARROW
    fun withWordsToTrainUnhappyPath() =
    )

    )
    

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84. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    words to train for all 7 languages
    huge system font size
    training
    

    item
    narrow screen
    trainingInfo =

    TrainingItem
    (
    
    trainingByLang = wordsToTrainPerLang(999_999)
    ,
    
    activeLangs = Language.values().toSet(
    )
    
    ),
    TrainingTestItem(
    fontSize = FontScale.HUGE,
    viewWidth = ViewWidth.NARROW
    )
    fun withWordsToTrainUnhappyPath() =
    )

    )
    

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85. aim to break the layout
    2
    Identifying unhappy paths
    thousand of words to train
    words to train for all 7 languages
    huge system font size
    narrow screen
    trainingInfo =

    TrainingItem
    (
    
    trainingByLang = wordsToTrainPerLang(999_999)
    ,
    
    activeLangs = Language.values().toSet(
    )
    
    ),
    TrainingTestItem(
    fontSize = FontScale.HUGE,
    viewWidth = ViewWidth.NARROW
    )

    )
    external
    fun withWordsToTrainUnhappyPath() =
    

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86. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    private fun ScreenshotTest.snapViewHolder(testItem: TrainingTestItem, snapshotName: String){
    val activity = FontsizeActivityScenario.launchWith(testItem.fontScale
    )
    
    .waitForActivity(),
    val view = waitForView {

    val layout = activity.inflate(R.layout.training_row)

    TrainingViewHolder(layout).apply
    {
    
    bind
    (
    
    trainingItem = testItem.trainingItem,

    languageClickedListener = null

    )
    
    }
    
    }
    compareScreenshot {

    holder = view,

    widthInPx = testItem.viewWidth.widthInPx
    ,
    
    name = snapshotName

    }
    }
    Test itself
    

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87. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    private fun ScreenshotTest.snapViewHolder(testItem: TrainingTestItem, snapshotName: String){
    val activity = FontsizeActivityScenario.launchWith(testItem.fontScale
    )
    
    .waitForActivity(),
    val view = waitForView {

    val layout = activity.inflate(R.layout.training_row)

    TrainingViewHolder(layout).apply
    {
    
    bind
    (
    
    trainingItem = testItem.trainingItem,

    languageClickedListener = null

    )
    
    }
    
    }
    compareScreenshot {

    holder = view,

    widthInPx = testItem.viewWidth.widthInPx
    ,
    
    name = snapshotName

    }
    }
    

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88. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    private fun ScreenshotTest.snapViewHolder(testItem: TrainingTestItem, snapshotName: String){
    val activity = FontsizeActivityScenario.launchWith(testItem.fontScale
    )
    
    .waitForActivity(),
    val view = waitForView {

    val layout = activity.inflate(R.layout.training_row)

    TrainingViewHolder(layout).apply
    {
    
    bind
    (
    
    trainingItem = testItem.trainingItem,

    languageClickedListener = null

    )
    
    }
    
    }
    compareScreenshot {

    holder = view,

    widthInPx = testItem.viewWidth.widthInPx
    ,
    
    name = snapshotName

    }
    }
    Wait for
    

    Ui thread
    

    idle
    +
    launch
    

    ActivityScenario
    

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89. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    private fun ScreenshotTest.snapViewHolder(testItem: TrainingTestItem, snapshotName: String){
    val activity = FontsizeActivityScenario.launchWith(testItem.fontScale
    )
    
    .waitForActivity(),
    val view = waitForView {

    val layout = activity.inflate(R.layout.training_row)

    TrainingViewHolder(layout).apply
    {
    
    bind
    (
    
    trainingItem = testItem.trainingItem,

    languageClickedListener = null

    )
    
    }
    
    }
    compareScreenshot {

    holder = view,

    widthInPx = testItem.viewWidth.widthInPx
    ,
    
    name = snapshotName

    }
    }
    Inflate view
    

    &
    
    
    bind data
    Wait for
    

    Ui thread
    

    idle
    +
    

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90. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    private fun ScreenshotTest.snapViewHolder(testItem: TrainingTestItem, snapshotName: String){
    val activity = FontsizeActivityScenario.launchWith(testItem.fontScale
    )
    
    .waitForActivity(),
    val view = waitForView {

    val layout = activity.inflate(R.layout.training_row)

    TrainingViewHolder(layout).apply
    {
    
    bind
    (
    
    trainingItem = testItem.trainingItem,

    languageClickedListener = null

    )
    
    }
    
    }
    compareScreenshot {

    holder = view,

    widthInPx = testItem.viewWidth.widthInPx
    ,
    
    name = snapshotName

    }
    }
    record
    
    
    screenshot
    

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91. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    private fun ScreenshotTest.snapViewHolder(testItem: TrainingTestItem, snapshotName: String){
    val activity = FontsizeActivityScenario.launchWith(testItem.fontScale
    )
    
    .waitForActivity(),
    val view = waitForView {

    val layout = activity.inflate(R.layout.training_row)

    TrainingViewHolder(layout).apply
    {
    
    bind
    (
    
    trainingItem = testItem.trainingItem,

    languageClickedListener = null

    )
    
    }
    
    }
    compareScreenshot {

    holder = view,

    widthInPx = testItem.viewWidth.widthInPx
    ,
    
    name = snapshotName

    }
    }
    

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92. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    @RunWith(Parameterized::class)

    class TrainingItemUnhappyPath(private val testItem: TrainingTestItem): ScreenshotTest{
    companion object {

    @JvmStatic

    @Parameterized.Parameter
    s
    
    fun testData(): Array =
    arrayOf
    (
    
    withWordsToTrainUnhappyPath()

    ..
    .
    
    )

    }
    @Test

    fun snapTrainingItem(){
    
    
    snapViewHolder(testItem)

    )
    }
    Parameterized
    

    tests
    

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93. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    @RunWith(Parameterized::class)

    class TrainingItemUnhappyPath(private val testItem: TrainingTestItem): ScreenshotTest{
    companion object {

    @JvmStatic

    @Parameterized.Parameter
    s
    
    fun testData(): Array =
    arrayOf
    (
    
    withWordsToTrainUnhappyPath()

    ..
    .
    
    )

    }
    @Test

    fun snapTrainingItem(){
    
    
    snapViewHolder(testItem)

    )
    }
    

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94. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    @RunWith(Parameterized::class)

    class TrainingItemUnhappyPath(private val testItem: TrainingTestItem): ScreenshotTest{
    companion object {

    @JvmStatic

    @Parameterized.Parameter
    s
    
    fun testData(): Array =
    arrayOf
    (
    
    withWordsToTrainUnhappyPath()

    ..
    .
    
    )

    }
    @Test

    fun snapTrainingItem(){
    
    
    snapViewHolder(testItem)

    )
    }
    set
    

    Runner
    

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95. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    @RunWith(Parameterized::class)

    class TrainingItemUnhappyPath(private val testItem: TrainingTestItem): ScreenshotTest{
    companion object {

    @JvmStatic

    @Parameterized.Parameter
    s
    
    fun testData(): Array =
    arrayOf
    (
    
    withWordsToTrainUnhappyPath()

    ..
    .
    
    )

    }
    @Test

    fun snapTrainingItem(){
    
    
    snapViewHolder(testItem)

    )
    }
    generate
    

    test data
    

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96. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    @RunWith(Parameterized::class)

    class TrainingItemUnhappyPath(private val testItem: TrainingTestItem): ScreenshotTest{
    companion object {

    @JvmStatic

    @Parameterized.Parameter
    s
    
    fun testData(): Array =
    arrayOf
    (
    
    withWordsToTrainUnhappyPath()

    ..
    .
    
    )

    }
    @Test

    fun snapTrainingItem(){
    
    
    snapViewHolder(testItem)

    )
    }
    test with
    

    parameter
    

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97. aim to break the layout
    2
    writing the snapshot test with pedrovgs/Shot
    @RunWith(Parameterized::class)

    class TrainingItemUnhappyPath(private val testItem: TrainingTestItem): ScreenshotTest{
    companion object {

    @JvmStatic

    @Parameterized.Parameter
    s
    
    fun testData(): Array =
    arrayOf
    (
    
    withWordsToTrainUnhappyPath()

    ..
    .
    
    )

    }
    @Test

    fun snapTrainingItem(){
    
    
    snapViewHolder(testItem)

    )
    }
    

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98. aim to break the layout
    2
    thousand of words to train
    words to train for all 7 languages
    huge system font size
    narrow screen
    recording unhappy path
    

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99. aim to break the layout
    2
    @RunWith(Parameterized::class)

    class TrainingItemUnhappyPath(private val testItem: TrainingTestItem): ScreenshotTest{
    companion object {

    @JvmStatic

    @Parameterized.Parameter
    s
    
    fun testData(): Array =
    arrayOf
    (
    
    withWordsToTrainUnhappyPath()

    ..
    .
    
    )

    }
    @Test

    fun snapTrainingItem(){
    
    
    snapViewHolder(testItem)

    )
    }
    recording happy and unhappy paths
    

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100. aim to break the layout
     2
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(private val testItem: TrainingTestItem): ScreenshotTest{
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(), withWordsToTrainHappyPath()

     withoutWordsToTrainUnhappyPath(), withoutWordsToTrainHappyPath(
     )
     
     )

     }
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     recording happy and unhappy paths
     

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101. aim to break the layout
     2
     recording happy and unhappy paths
     without WordsToTrain HappyPath()
     with WordsToTrain HappyPath() with WordsToTrain UnhappyPath()
     without WordsToTrain UnhappyPath()
     

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102. group tests by relevance
     3
     

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103. 2’ 100 happy + unhappy
     group tests by relevance
     3
     100%
     

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104. 2’
     4’ 200
     100 happy + unhappy
     group tests by relevance
     3
     100%
     

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105. 2’
     4’
     8’ 400
     200
     100 happy + unhappy
     group tests by relevance
     3
     100%
     

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106. 2’
     4’
     8’
     16’ 800
     400
     200
     100 happy + unhappy
     group tests by relevance
     3
     100%
     

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107. 2’
     4’
     8’
     16’
     …
     800
     400
     200
     100 happy + unhappy
     100%
     group tests by relevance
     3
     

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108. 2’
     4’
     8’
     16’ 800
     400
     200
     100
     group tests by relevance
     3
     unhappy
     happy 90 - 100%
     5 - 20%
     …
     

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109. 2’
     …
     1’
     3’
     40
     80
     160
     320
     6’
     unhappy
     happy 90 - 100%
     5 - 20%
     group tests by relevance
     3
     

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110. daily builds night build
     

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111. night build
     run happy path tests ONLY
     catch most important bugs
     run on every PR
     daily builds
     

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112. night build
     run happy path tests ONLY
     catch most important bugs
     run on every PR
     run unhappy path tests ONLY
     catch less important bugs
     run once a day
     daily builds
     

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113. night build
     run happy path tests ONLY
     catch most important bugs
     run on every PR
     run unhappy path tests ONLY
     catch less important bugs
     run once a day
     daily builds
     fast development cycles
     

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114. 3
     unhappy vs. happy path
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     group tests by relevance
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(), withWordsToTrainHappyPath()

     withoutWordsToTrainUnhappyPath(), withoutWordsToTrainHappyPath(
     )
     
     )

     }
     Filtered
     
     
     parameterized
     

     tests
     

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115. 3
     unhappy vs. happy path
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     group tests by relevance
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(), withWordsToTrainHappyPath()

     withoutWordsToTrainUnhappyPath(), withoutWordsToTrainHappyPath(
     )
     
     )

     }
     

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116. 3
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     group tests by relevance
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(), withWordsToTrainHappyPath()

     withoutWordsToTrainUnhappyPath(), withoutWordsToTrainHappyPath(
     )
     
     )

     }
     unhappy vs. happy path
     

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117. 3
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     group tests by relevance
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(),

     withoutWordsToTrainUnhappyPath(
     )
     
     )

     }
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainHappyPath()

     withoutWordsToTrainHappyPath(
     )
     
     )

     }
     @RunWith(Parameterized::class)

     class TrainingItemHappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     unhappy vs. happy path
     

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118. 3
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     group tests by relevance
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(),

     withoutWordsToTrainUnhappyPath(
     )
     
     )

     }
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainHappyPath()

     withoutWordsToTrainHappyPath(
     )
     
     )

     }
     @RunWith(Parameterized::class)

     class TrainingItemHappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     unhappy vs. happy path
     

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119. 3
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @UnhappyPat
     h
     
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     group tests by relevance
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(),

     withoutWordsToTrainUnhappyPath(
     )
     
     )

     }
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainHappyPath()

     withoutWordsToTrainHappyPath(
     )
     
     )

     }
     @RunWith(Parameterized::class)

     class TrainingItemHappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @HappyPat
     h
     
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     unhappy vs. happy path
     

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120. 3
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @UnhappyPat
     h
     
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     group tests by relevance
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(),

     withoutWordsToTrainUnhappyPath(
     )
     
     )

     }
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainHappyPath()

     withoutWordsToTrainHappyPath(
     )
     
     )

     }
     @RunWith(Parameterized::class)

     class TrainingItemHappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @HappyPat
     h
     
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     = path.to.annotation.UnhappyPath
     -Pandroid.testIntrumentationRunnerArguments.annotation
     ./gradlew -Precord
     unhappy vs. happy path
     

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121. 3
     @RunWith(Parameterized::class)

     class TrainingItemUnhappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @UnhappyPat
     h
     
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     group tests by relevance
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainUnhappyPath(),

     withoutWordsToTrainUnhappyPath(
     )
     
     )

     }
     companion object {

     @JvmStatic

     @Parameterized.Parameter
     s
     
     fun testData(): Array =
     arrayOf
     (
     
     withWordsToTrainHappyPath()

     withoutWordsToTrainHappyPath(
     )
     
     )

     }
     @RunWith(Parameterized::class)

     class TrainingItemHappyPath(

     private val testItem: TrainingTestItem

     ): ScreenshotTest{
     @HappyPat
     h
     
     @Test

     fun snapTrainingItem(){
     
     
     snapViewHolder(testItem)

     )
     }
     = path.to.annotation.HappyPath
     -Pandroid.testIntrumentationRunnerArguments.annotation
     ./gradlew -Precord
     unhappy vs. happy path
     

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122. 1
     Snapshot testing
     effectively
     2
     Start small & simple
     Aim to break the layout
     3 Group tests by relevance
     

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123. attention
     for your
     THANKS
     

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124. code
     blogs
     @SergioSastre
     @sergio-sastre
     @sergio-sastre
     @Gio_Sastre
     Sergio Sastre Flórez
     Lead & Senior
     Android developer appdev.de
     

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