From 0c8eefef0cffe5109688d673d70d3b97d31d1d53 Mon Sep 17 00:00:00 2001
From: Paul Rangger <48455539+PaRangger@users.noreply.github.com>
Date: Sat, 14 Dec 2024 12:06:27 +0100
Subject: [PATCH] Communication: Fix scrolling error for long messages (#9997)

---
 .../conversation-messages.component.ts                   | 2 +-
 .../conversation-messages.component.spec.ts              | 9 +++++++++
 2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/src/main/webapp/app/overview/course-conversations/layout/conversation-messages/conversation-messages.component.ts b/src/main/webapp/app/overview/course-conversations/layout/conversation-messages/conversation-messages.component.ts
index 17342052df52..ddac0b0efacb 100644
--- a/src/main/webapp/app/overview/course-conversations/layout/conversation-messages/conversation-messages.component.ts
+++ b/src/main/webapp/app/overview/course-conversations/layout/conversation-messages/conversation-messages.component.ts
@@ -441,7 +441,7 @@ export class ConversationMessagesComponent implements OnInit, AfterViewInit, OnD
             }
         }
         this.elementsAtScrollPosition = visibleMessages;
-        if (this.elementsAtScrollPosition && this.canStartSaving) {
+        if (this.elementsAtScrollPosition && this.elementsAtScrollPosition.length > 0 && this.canStartSaving) {
             this.saveScrollPosition(this.elementsAtScrollPosition[0].post.id!);
         }
     }
diff --git a/src/test/javascript/spec/component/overview/course-conversations/layout/conversation-messages/conversation-messages.component.spec.ts b/src/test/javascript/spec/component/overview/course-conversations/layout/conversation-messages/conversation-messages.component.spec.ts
index 9884da1a010a..815c5d9a4501 100644
--- a/src/test/javascript/spec/component/overview/course-conversations/layout/conversation-messages/conversation-messages.component.spec.ts
+++ b/src/test/javascript/spec/component/overview/course-conversations/layout/conversation-messages/conversation-messages.component.spec.ts
@@ -284,5 +284,14 @@ examples.forEach((activeConversation) => {
                 expect(inlineInput).toBeTruthy(); // Check if the inline input component is present
             }));
         }
+
+        it('should scroll to bottom and set canStartSaving to true when lastScrollPosition is falsy', async () => {
+            const scrollToBottomSpy = jest.spyOn(component, 'scrollToBottomOfMessages');
+
+            await component.goToLastSelectedElement(0, false);
+
+            expect(scrollToBottomSpy).toHaveBeenCalledOnce();
+            expect(component.canStartSaving).toBeTrue();
+        });
     });
 });