fix: clarify the meaning of isParentMessage (#596)

[UIKIT-4028](https://sendbird.atlassian.net/browse/UIKIT-4028)

Author: HoonBaek

src/utils/__tests__/isParentMessage.spec.ts

@@ -13,7 +13,7 @@ const mockParentMessage = {
   threadInfo: {
     lastRepliedAt: 0,
     mostRepliedUsers: [],
-    replyCount: 0,
+    replyCount: 3,
     updatedAt: 0,
   },
 };
@@ -24,11 +24,18 @@ const mockThreadMessage = {
 };
 
 describe('Global-utils/isParentMessage', () => {
-  it('should verify thread message', () => {
+  it('should verify parent message', () => {
     expect(
       isParentMessage(mockParentMessage as unknown as UserMessage),
     ).toBeTrue();
   });
+  it('should return false when the message does not have replyCount', () => {
+    const normalMessage = { ...mockParentMessage };
+    normalMessage.threadInfo.replyCount = 0;
+    expect(
+      isParentMessage(normalMessage as unknown as UserMessage),
+    ).toBeFalse();
+  });
   it('should filter the other messages', () => {
     expect(
       isParentMessage(mockNormalMessage as unknown as UserMessage),

src/utils/index.ts

@@ -137,7 +137,7 @@ export const isFileMessage = (message: AdminMessage | UserMessage | FileMessage)
   message && (message?.isFileMessage?.() || (message?.messageType === 'file'))
 );
 export const isParentMessage = (message: AdminMessage | UserMessage | FileMessage): boolean => (
-  !message.parentMessageId && !message.parentMessage && message.threadInfo !== null
+  !message.parentMessageId && !message.parentMessage && (message.threadInfo?.replyCount ?? 0) > 0
 );
 export const isThreadMessage = (message: AdminMessage | UserMessage | FileMessage): boolean => (
   !!message.parentMessageId && !!message.parentMessage