Fix #2209: Create a Helper class to provide methos for [RecyclerViewActions] scrolling actions

testing/build.gradle

@@ -51,7 +51,9 @@ dependencies {
   implementation(
       'androidx.annotation:annotation:1.1.0',
       'androidx.lifecycle:lifecycle-livedata-ktx:2.2.0-alpha03',
+      'androidx.recyclerview:recyclerview:1.0.0',
       'androidx.test.espresso:espresso-core:3.2.0',
+      'androidx.test.espresso:espresso-contrib:3.2.0',
       'androidx.test:runner:1.2.0',
       'com.google.dagger:dagger:2.24',
       'com.google.truth:truth:0.43',

testing/src/main/java/org/oppia/android/testing/RecyclerViewScrollingActions.kt

@@ -0,0 +1,51 @@
+package org.oppia.android.testing
+
+import androidx.annotation.LayoutRes
+import androidx.recyclerview.widget.RecyclerView
+import androidx.test.espresso.Espresso.onView
+import androidx.test.espresso.action.ViewActions.scrollTo
+import androidx.test.espresso.contrib.RecyclerViewActions.actionOnItemAtPosition
+import androidx.test.espresso.contrib.RecyclerViewActions.scrollToHolder
+import androidx.test.espresso.matcher.ViewMatchers.withId
+import org.hamcrest.BaseMatcher
+import javax.inject.Inject
+
+/**
+ * Provides different scrolling actions for [RecyclerView]s. This is needed because different
+ * testing scenarios potentially require different scrolling actions for the tests to be successful.
+ * Use the methods in this class for all scrolling actions for [RecyclerView]s in Roboelectric and
+ * Espresso test scenarios. See #2209 for more information.
+ */
+class RecyclerViewScrollingActions @Inject constructor(
+  val testCoroutineDispatchers: TestCoroutineDispatchers
+) {
+
+  /**
+   * Performs scrolling action to particular RecyclerView at a required position. Use this method
+   * for all testing scenarios when scrolling to a RecyclerView at a particular position.
+   */
+  fun scrollToPosition(@LayoutRes recyclerViewId: Int, position: Int) {
+    onView(withId(recyclerViewId)).perform(
+      actionOnItemAtPosition<RecyclerView.ViewHolder>(
+        position,
+        scrollTo()
+      )
+    )
+    testCoroutineDispatchers.runCurrent()
+  }
+
+  /**
+   * Performs scrolling action to [RecyclerView] of a particular ViewType designed by a view holder
+   * via [baseMatcher]. Use this method for all testing scenarios when the [View] type of the
+   * destination [RecyclerView] is known.
+   */
+  fun scrollToViewType(
+    @LayoutRes recyclerViewId: Int,
+    baseMatcher: BaseMatcher<RecyclerView.ViewHolder>
+  ) {
+    onView(withId(recyclerViewId)).perform(
+      scrollToHolder(baseMatcher)
+    )
+    testCoroutineDispatchers.runCurrent()
+  }
+}