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Alex Rupérez

Published: 04 Jun 09:14
I starred agoda-com/Kakao at GitHub.
Nice and simple DSL for Espresso in Kotlin
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Nice and simple DSL for Espresso in Kotlin


At Agoda, we have more than 1000 automated tests to ensure our application's quality and give our best experience to the user. All of them are written with Espresso from Google. Even though Espresso is working really well with our test, the code readability is quite low. Let's look at some of the examples of how we write the test.

onView(allOf(withId(, hasDescendant(withText("Standard Rate"))))

This is an example just to check the visibility and you can see that it's not looking that good. As Agoda developers, we want to improve not just our codebase quality, but also our implementation of tests as well. This is why we are introducing Kakao. The library that will make you enjoy writing automated tests like you are drinking a hot chocolate.



  • Readability
  • Reusability
  • Extensible DSL

How to use it

Create Screen

Create your entity Screen where you will add the views involved in the interactions of the tests:

class FormScreen : Screen<FormScreen>()

Screen can represent the whole user interface or a portion of UI. If you are using Page Object pattern you can put the interactions of Kakao inside the Page Objects.

Create KViews

Screen contains KViews, these are the Android Framework views where you want to do the interactions:

class FormScreen : Screen<FormScreen>() {
    val phone = KView { withId( }
    val email = KEditText { withId( }
    val submit = KButton { withId( }

Kakao provides different types depending on the type of view:

  • KView
  • KEditText
  • KTextView
  • KButton
  • KImageView
  • KWebView
  • KCheckbox
  • KViewPager
  • KSeekBar
  • and more

Every KView contains matchers to retrieve the view involved in the ViewInteraction. Some examples of matchers provided by Kakao:

  • withId
  • withText
  • withContentDescription
  • withDrawable
  • withBackgroundColor
  • and more

Like in Espresso you can combine different matchers:

val email = KEditText { 

And you can use your custom matchers:

val email = KEditText { 
    matches { MyCustomMatcher.matches(position) }

Write the interaction.

The syntax of the test with Kakao is very easy, once you have the Screen and the KViews defined, you only have to apply the actions or assertions like in Espresso:

onScreen<FormScreen> {
    phone {
    button {

Kakao provides multiple actions/assertions based on Espresso. Furthermore, you can combine them, just like the matchers. You can use your custom assertions or your custom actions too:

onScreen<FormScreen> {
    phone {
       assert { MyCustomAssertion.isThaiNumber() }
    button {
       act { MyCustomAction.clickOnTheCorner() }



Kakao offers an easy way to interact with your RecyclerViews and ListViews

Create the KListView/KRecyclerView

Inside your Screen create the KView matching with your view:

For KListView:

val list = KListView ({
           builder = { withId( } })

For KRecyclerView:

val myList = KRecyclerView ({
             builder = { withId( } })

You can combine different matchers to retrieve your view.

Create KAdapterItem/KRecyclerItem

Every adapter contains different Items, Kakao provides an easy way to define the different items of your adapter with KAdapterItem and KRecyclerItem. If your adapter contains multiple Items but your interactions in your tests only work with one is not required to create all of them.


class Item(i: DataInteraction) : KAdapterItem<Item>(i) {
    val title = KTextView(i) { withId( }
    val subtitle = KTextView(i) { withId( }
    val button = KButton(i) { withId( }


class Item(parent: Matcher<View>) : KRecyclerItem<Item>(parent) {
    val title: KTextView = KTextView(parent) { withId( }
    val subtitle: KTextView = KTextView(parent) { withId( }

The KView defined in the Item corresponds views used on the Item. You can assign the KItems to the KListView/ KRecyclerView like:

val recycler: KRecyclerView = KRecyclerView({
}, itemTypeBuilder = {

And finally your final interaction will be:

onScreen<RecyclerScreen> {
    recycler {
        firstChild<TestRecyclerScreen.Item> {
            title { hasText("Title 1") }

Kakao provides different accessors in the adapter:

  • childAt
  • firstChild
  • lastChild
  • childWith
Custom KViews

If you have custom Views in your tests and you want to create your own KView, we have KBaseView. Just extend this class and implement as much additional Action/Assertion interfaces as you want. You also need to override constructors that you need.

class KMyView : KBaseView<KView>, MyActions, MyAssertions {
    constructor(function: ViewBuilder.() -> Unit) : super(function)
    constructor(parent: Matcher<View>, function: ViewBuilder.() -> Unit) : super(parent, function)
    constructor(parent: DataInteraction, function: ViewBuilder.() -> Unit) : super(parent, function)




or Gradle:

repositories {
dependencies {
    // For Gradle Version below 3.0.0
    androidTestCompile 'com.agoda.kakao:kakao:2.0.0'

    // For Gradle Version 3.0.0 or above
    androidTestImplementation 'com.agoda.kakao:kakao:2.0.0'


Default artifact starting from 2.0.0 includes AndroidX libraries to build upon. If you're still using old support libraries, please use 2.0.0-support artifact.

dependencies {
    androidTestImplementation 'com.agoda.kakao:kakao:2.0.0-support'

We will move to AndroidX dependencies in the major release as soon as Google will publish stable release.

Contribution Policy

Kakao is an open source project, and depends on its users to improve it. We are more than happy to find you interested in taking the project forward.

Kindly refer to the Contribution Guidelines for detailed information.

Code of Conduct

Please refer to Code of Conduct document.


Kakao is open source and available under the Apache License, Version 2.0.

Thanks to