Android - LHN - Fix chats created offline

src/libs/ReportUtils.ts

@@ -4567,21 +4567,34 @@ function getInvoicesChatName({
 }
 
 /**
- * Get the title for a report using only participant names. This may be used for 1:1 DMs and other non-categorized chats.
- */
-function buildReportNameFromParticipantNames({report, personalDetails}: {report: OnyxEntry<Report>; personalDetails?: Partial<PersonalDetailsList>}) {
-    const participantsWithoutCurrentUser: number[] = [];
-    Object.keys(report?.participants ?? {}).forEach((accountID) => {
-        const accID = Number(accountID);
-        if (accID !== currentUserAccountID && participantsWithoutCurrentUser.length < 5) {
-            participantsWithoutCurrentUser.push(accID);
-        }
-    });
-    const isMultipleParticipantReport = participantsWithoutCurrentUser.length > 1;
-    return participantsWithoutCurrentUser
-        .map((accountID) => getDisplayNameForParticipant({accountID, shouldUseShortForm: isMultipleParticipantReport, personalDetailsData: personalDetails}))
-        .join(', ');
-}
+ * Generates a report title using the names of participants, excluding the current user.
+ * This function is useful in contexts such as 1:1 direct messages (DMs) or other group chats.
+ * It limits to a maximum of 5 participants for the title and uses short names unless there is only one participant.
+ */
+const buildReportNameFromParticipantNames = ({report, personalDetails: personalDetailsData}: {report: OnyxEntry<Report>; personalDetails?: Partial<PersonalDetailsList>}) =>
+    Object.keys(report?.participants ?? {})
+        .map(Number)
+        .filter((id) => id !== currentUserAccountID)
+        .slice(0, 5)
+        .map((accountID) => ({
+            accountID,
+            name: getDisplayNameForParticipant({
+                accountID,
+                shouldUseShortForm: true,
+                personalDetailsData,
+            }),
+        }))
+        .filter((participant) => participant.name)
+        .reduce((formattedNames, {name, accountID}, _, array) => {
+            // If there is only one participant (if it is 0 or less the function will return empty string), return their full name
+            if (array.length < 2) {
+                return getDisplayNameForParticipant({
+                    accountID,
+                    personalDetailsData,
+                });
+            }
+            return formattedNames ? `${formattedNames}, ${name}` : name;
+        }, '');
 
 function generateReportName(report: OnyxEntry<Report>): string {
     if (!report) {

tests/unit/ReportUtilsTest.ts

@@ -1,4 +1,5 @@
 /* eslint-disable @typescript-eslint/naming-convention */
+import {beforeAll} from '@jest/globals';
 import {renderHook} from '@testing-library/react-native';
 import {addDays, format as formatDate} from 'date-fns';
 import type {OnyxCollection, OnyxEntry} from 'react-native-onyx';
@@ -13,6 +14,7 @@ import {
     buildOptimisticExpenseReport,
     buildOptimisticIOUReportAction,
     buildParticipantsFromAccountIDs,
+    buildReportNameFromParticipantNames,
     buildTransactionThread,
     canDeleteReportAction,
     canEditWriteCapability,
@@ -49,7 +51,9 @@ import CONST from '@src/CONST';
 import ONYXKEYS from '@src/ONYXKEYS';
 import type {Beta, OnyxInputOrEntry, PersonalDetailsList, Policy, PolicyEmployeeList, Report, ReportAction, Transaction} from '@src/types/onyx';
 import type {ErrorFields, Errors} from '@src/types/onyx/OnyxCommon';
+import type {Participant} from '@src/types/onyx/Report';
 import {toCollectionDataSet} from '@src/types/utils/CollectionDataSet';
+import {chatReportR14932 as mockedChatReport} from '../../__mocks__/reportData/reports';
 import * as NumberUtils from '../../src/libs/NumberUtils';
 import {convertedInvoiceChat} from '../data/Invoice';
 import createRandomPolicy from '../utils/collections/policies';
@@ -2456,4 +2460,67 @@ describe('ReportUtils', () => {
             expect(isArchivedNonExpenseReportWithID(archivedChatReport, isReportArchived.current)).toBe(true);
         });
     });
+
+    describe('buildReportNameFromParticipantNames', () => {
+        /**
+         * Generates a fake report and matching personal details for specified number of participants.
+         * Participants in the report are directly linked with their personal details.
+         */
+        const generateFakeReportAndParticipantsPersonalDetails = ({count, start = 0}: {count: number; start?: number}): {report: Report; personalDetails: PersonalDetailsList} => {
+            const data = {
+                report: {
+                    ...mockedChatReport,
+                    participants: Object.keys(fakePersonalDetails)
+                        .slice(start, count)
+                        .reduce<Record<string, Participant>>((acc, cur) => {
+                            acc[cur] = {notificationPreference: CONST.REPORT.NOTIFICATION_PREFERENCE.ALWAYS};
+                            return acc;
+                        }, {}),
+                },
+                personalDetails: Object.fromEntries(Object.entries(fakePersonalDetails).slice(start, count)),
+            };
+
+            data.personalDetails[currentUserAccountID] = {
+                accountID: currentUserAccountID,
+                displayName: 'CURRENT USER',
+                firstName: 'CURRENT',
+            };
+
+            return data;
+        };
+
+        it('excludes the current user from the report title', () => {
+            const result = buildReportNameFromParticipantNames(generateFakeReportAndParticipantsPersonalDetails({count: currentUserAccountID + 2}));
+            expect(result).not.toContain('CURRENT');
+        });
+
+        it('limits to a maximum of 5 participants in the title', () => {
+            const result = buildReportNameFromParticipantNames(generateFakeReportAndParticipantsPersonalDetails({count: 10}));
+            expect(result.split(',').length).toBeLessThanOrEqual(5);
+        });
+
+        it('returns full name if only one participant is present (excluding current user)', () => {
+            const result = buildReportNameFromParticipantNames(generateFakeReportAndParticipantsPersonalDetails({count: 1}));
+            const {displayName} = fakePersonalDetails[1] ?? {};
+            expect(result).toEqual(displayName);
+        });
+
+        it('returns an empty string if there are no participants or all are excluded', () => {
+            const result = buildReportNameFromParticipantNames(generateFakeReportAndParticipantsPersonalDetails({start: currentUserAccountID - 1, count: 1}));
+            expect(result).toEqual('');
+        });
+
+        it('handles partial or missing personal details correctly', () => {
+            const {report} = generateFakeReportAndParticipantsPersonalDetails({count: 6});
+
+            const secondUser = fakePersonalDetails[2];
+            const fourthUser = fakePersonalDetails[4];
+
+            const incompleteDetails = {2: secondUser, 4: fourthUser};
+            const result = buildReportNameFromParticipantNames({report, personalDetails: incompleteDetails});
+            const expectedNames = [secondUser?.firstName, fourthUser?.firstName].sort();
+            const resultNames = result.split(', ').sort();
+            expect(resultNames).toEqual(expect.arrayContaining(expectedNames));
+        });
+    });
 });