Add test to ensure that TimelineView loads more Events.

features/messages/impl/src/main/kotlin/io/element/android/features/messages/impl/timeline/TimelineStateProvider.kt

@@ -45,23 +45,35 @@ import kotlinx.collections.immutable.toPersistentList
 import java.util.UUID
 import kotlin.random.Random
 
-fun aTimelineState(timelineItems: ImmutableList<TimelineItem> = persistentListOf()) = TimelineState(
+fun aTimelineState(
+    timelineItems: ImmutableList<TimelineItem> = persistentListOf(),
+    paginationState: MatrixTimeline.PaginationState = aPaginationState(),
+    eventSink: (TimelineEvents) -> Unit = {},
+) = TimelineState(
     timelineItems = timelineItems,
     timelineRoomInfo = aTimelineRoomInfo(),
-    paginationState = MatrixTimeline.PaginationState(
+    paginationState = paginationState,
-        isBackPaginating = false,
-        hasMoreToLoadBackwards = true,
-        beginningOfRoomReached = false,
-    ),
     highlightedEventId = null,
     newEventState = NewEventState.None,
     sessionState = aSessionState(
         isSessionVerified = true,
         isKeyBackupEnabled = true,
     ),
-    eventSink = {},
+    eventSink = eventSink,
 )
 
+fun aPaginationState(
+    isBackPaginating: Boolean = false,
+    hasMoreToLoadBackwards: Boolean = true,
+    beginningOfRoomReached: Boolean = false,
+): MatrixTimeline.PaginationState {
+    return MatrixTimeline.PaginationState(
+        isBackPaginating = isBackPaginating,
+        hasMoreToLoadBackwards = hasMoreToLoadBackwards,
+        beginningOfRoomReached = beginningOfRoomReached,
+    )
+}
+
 internal fun aTimelineItemList(content: TimelineItemEventContent): ImmutableList<TimelineItem> {
     return persistentListOf(
         // 3 items (First Middle Last) with isMine = false

features/messages/impl/src/test/kotlin/io/element/android/features/messages/impl/timeline/TimelineViewTest.kt

@@ -0,0 +1,83 @@
+/*
+ * Copyright (c) 2024 New Vector Ltd
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package io.element.android.features.messages.impl.timeline
+
+import androidx.activity.ComponentActivity
+import androidx.compose.ui.test.junit4.createAndroidComposeRule
+import androidx.test.ext.junit.runners.AndroidJUnit4
+import io.element.android.tests.testutils.EnsureNeverCalledWithParam
+import io.element.android.tests.testutils.EnsureNeverCalledWithTwoParams
+import io.element.android.tests.testutils.EventsRecorder
+import org.junit.Rule
+import org.junit.Test
+import org.junit.runner.RunWith
+
+@RunWith(AndroidJUnit4::class)
+class TimelineViewTest {
+    @get:Rule val rule = createAndroidComposeRule<ComponentActivity>()
+
+    @Test
+    fun `reaching the end of the timeline with more events to load emits a LoadMore event`() {
+        val eventsRecorder = EventsRecorder<TimelineEvents>()
+        rule.setContent {
+            TimelineView(
+                aTimelineState(
+                    eventSink = eventsRecorder,
+                    paginationState = aPaginationState(
+                        hasMoreToLoadBackwards = true,
+                    )
+                ),
+                roomName = null,
+                onUserDataClicked = EnsureNeverCalledWithParam(),
+                onMessageClicked = EnsureNeverCalledWithParam(),
+                onMessageLongClicked = EnsureNeverCalledWithParam(),
+                onTimestampClicked = EnsureNeverCalledWithParam(),
+                onSwipeToReply = EnsureNeverCalledWithParam(),
+                onReactionClicked = EnsureNeverCalledWithTwoParams(),
+                onReactionLongClicked = EnsureNeverCalledWithTwoParams(),
+                onMoreReactionsClicked = EnsureNeverCalledWithParam(),
+                onReadReceiptClick = EnsureNeverCalledWithParam(),
+            )
+        }
+        eventsRecorder.assertSingle(TimelineEvents.LoadMore)
+    }
+
+    @Test
+    fun `reaching the end of the timeline does not send a LoadMore event`() {
+        val eventsRecorder = EventsRecorder<TimelineEvents>(expectEvents = false)
+        rule.setContent {
+            TimelineView(
+                aTimelineState(
+                    eventSink = eventsRecorder,
+                    paginationState = aPaginationState(
+                        hasMoreToLoadBackwards = false,
+                    )
+                ),
+                roomName = null,
+                onUserDataClicked = EnsureNeverCalledWithParam(),
+                onMessageClicked = EnsureNeverCalledWithParam(),
+                onMessageLongClicked = EnsureNeverCalledWithParam(),
+                onTimestampClicked = EnsureNeverCalledWithParam(),
+                onSwipeToReply = EnsureNeverCalledWithParam(),
+                onReactionClicked = EnsureNeverCalledWithTwoParams(),
+                onReactionLongClicked = EnsureNeverCalledWithTwoParams(),
+                onMoreReactionsClicked = EnsureNeverCalledWithParam(),
+                onReadReceiptClick = EnsureNeverCalledWithParam(),
+            )
+        }
+    }
+}

tests/testutils/src/main/kotlin/io/element/android/tests/testutils/EnsureNeverCalled.kt

@@ -27,3 +27,9 @@ class EnsureNeverCalledWithParam<T> : (T) -> Unit {
         throw AssertionError("Should not be called and is called with $p1")
     }
 }
+
+class EnsureNeverCalledWithTwoParams<T, U> : (T, U) -> Unit {
+    override fun invoke(p1: T, p2: U) {
+        throw AssertionError("Should not be called and is called with $p1 and $p2")
+    }
+}