add RecyclerViewSampleKtTest

ui/espresso/RecyclerViewSample/app/build.gradle

@@ -16,6 +16,10 @@
 
 apply plugin: 'com.android.application'
 
+apply plugin: 'kotlin-android'
+
+apply plugin: 'kotlin-android-extensions'
+
 android {
     compileSdkVersion 30
     buildToolsVersion rootProject.buildToolsVersion
@@ -40,15 +44,24 @@ android {
     }
 }
 
+tasks.withType(org.jetbrains.kotlin.gradle.tasks.KotlinCompile).all {
+    kotlinOptions {
+        jvmTarget = "1.8"
+    }
+}
+
 dependencies {
     // App dependencies
     implementation 'androidx.annotation:annotation:' + rootProject.androidxAnnotationVersion;
     implementation 'androidx.recyclerview:recyclerview:' + rootProject.androidxRecyclerVersion;
     implementation 'androidx.multidex:multidex:2.0.1'
 
     // Testing-only dependencies
+    androidTestImplementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlinVersion";
     androidTestImplementation 'androidx.test:core:' + rootProject.coreVersion;
+    androidTestImplementation 'androidx.test:core-ktx:' + rootProject.coreVersion;
     androidTestImplementation 'androidx.test.ext:junit:' + rootProject.extJUnitVersion;
+    androidTestImplementation 'androidx.test.ext:junit-ktx:' + rootProject.extJUnitVersion;
     androidTestImplementation 'androidx.test:runner:' + rootProject.runnerVersion;
     androidTestImplementation 'androidx.test.espresso:espresso-core:' + rootProject.espressoVersion;
     androidTestImplementation 'androidx.test.espresso:espresso-contrib:' + rootProject.espressoVersion;

ui/espresso/RecyclerViewSample/app/src/androidTest/java/com/example/android/testing/espresso/RecyclerViewSample/RecyclerViewSampleKtTest.kt

@@ -0,0 +1,81 @@
+package com.example.android.testing.espresso.RecyclerViewSample
+
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.PerformException
+import androidx.test.espresso.action.ViewActions.click
+import androidx.test.espresso.assertion.ViewAssertions.matches
+import androidx.test.espresso.contrib.RecyclerViewActions
+import androidx.test.espresso.matcher.ViewMatchers.*
+import androidx.test.ext.junit.rules.activityScenarioRule
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import androidx.test.filters.LargeTest
+import org.hamcrest.Description
+import org.hamcrest.Matcher
+import org.hamcrest.TypeSafeMatcher
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+@LargeTest
+class RecyclerViewSampleKtTest {
+
+    /**
+     * Use {@link ActivityScenario} to create and launch the activity under test. This is a
+     * replacement for {@link androidx.test.rule.ActivityTestRule}.
+     */
+    @get:Rule
+    var activityScenarioRule = activityScenarioRule<MainActivity>()
+
+    @Test(expected = PerformException::class)
+    fun itemWithText_doesNotExist() {
+        // Attempt to scroll to an item that contains the special text.
+        onView(withId(R.id.recyclerView))
+            // scrollTo will fail the test if no item matches.
+            .perform(RecyclerViewActions.scrollTo<CustomAdapter.ViewHolder>(
+                    hasDescendant(withText("not in the list"))
+            ))
+    }
+
+    @Test
+    fun scrollToItemBelowFold_checkItsText() {
+        // First scroll to the position that needs to be matched and click on it.
+        onView(withId(R.id.recyclerView))
+            .perform(RecyclerViewActions.actionOnItemAtPosition<CustomAdapter.ViewHolder>(ITEM_BELOW_THE_FOLD, click()))
+
+        // Match the text in an item below the fold and check that it's displayed.
+        val itemElementText = "This is element #${ITEM_BELOW_THE_FOLD}"
+        onView(withText(itemElementText)).check(matches(isDisplayed()))
+    }
+
+    @Test
+    fun itemInMiddleOfList_hasSpecialText() {
+        // First, scroll to the view holder using the isInTheMiddle matcher.
+        onView(withId(R.id.recyclerView))
+            .perform(RecyclerViewActions.scrollToHolder(isInTheMiddle()))
+
+        // Check that the item has the special text.
+        val middleElementText = "This is the middle!"
+        onView(withText(middleElementText)).check(matches(isDisplayed()))
+    }
+
+    /**
+     * Matches the {@link CustomAdapter.ViewHolder}s in the middle of the list.
+     */
+    private fun isInTheMiddle(): Matcher<CustomAdapter.ViewHolder> {
+        return object: TypeSafeMatcher<CustomAdapter.ViewHolder>() {
+            override fun matchesSafely(customHolder: CustomAdapter.ViewHolder): Boolean {
+                return customHolder.isInTheMiddle
+            }
+
+            override fun describeTo(description: Description) {
+                description.appendText("item in the middle")
+            }
+        }
+    }
+
+    companion object {
+        val ITEM_BELOW_THE_FOLD = 40
+    }
+
+}

ui/espresso/RecyclerViewSample/build.gradle

@@ -17,6 +17,7 @@
 // Top-level build file where you can add configuration options common to all sub-projects/modules.
 
 buildscript {
+    ext.kotlinVersion = "1.6.10"
     ext.agpVersion = "7.3.0-alpha07"
     repositories {
         // Insert local test repo here
@@ -25,6 +26,7 @@ buildscript {
     }
     dependencies {
         classpath "com.android.tools.build:gradle:$agpVersion"
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlinVersion"
 
         // NOTE: Do not place your application dependencies here; they belong
         // in the individual module build.gradle files