Fix double OpenReport call when comment linking, enable test

jest/setup.ts

@@ -1,3 +1,4 @@
+/* eslint-disable max-classes-per-file */
 import '@shopify/flash-list/jestSetup';
 import 'react-native-gesture-handler/jestSetup';
 import type * as RNKeyboardController from 'react-native-keyboard-controller';
@@ -78,3 +79,22 @@ jest.mock('@src/libs/actions/Timing', () => ({
     start: jest.fn(),
     end: jest.fn(),
 }));
+
+// This makes FlatList render synchronously for easier testing.
+jest.mock(
+    '@react-native/virtualized-lists/Interaction/Batchinator',
+    () =>
+        class SyncBachinator {
+            #callback: () => void;
+
+            constructor(callback: () => void) {
+                this.#callback = callback;
+            }
+
+            schedule() {
+                this.#callback();
+            }
+
+            dispose() {}
+        },
+);

src/pages/home/ReportScreen.tsx

@@ -522,10 +522,9 @@ function ReportScreen({route, currentReportID = '', navigation}: ReportScreenPro
 
     useEffect(() => {
         // Call OpenReport only if we are not linking to a message or the report is not available yet
-        if (isLoadingReportOnyx || (reportActionIDFromRoute && report.reportID && isLinkedMessagePageReady)) {
+        if (isLoadingReportOnyx || reportActionIDFromRoute) {
             return;
         }
-
         fetchReportIfNeeded();
         // eslint-disable-next-line react-compiler/react-compiler, react-hooks/exhaustive-deps
     }, [isLoadingReportOnyx]);

tests/ui/PaginationTest.tsx

@@ -309,9 +309,7 @@ describe('Pagination', () => {
         expect(getReportActions()).toHaveLength(18);
     });
 
-    // Currently broken on main by https://github.com/Expensify/App/pull/42582.
-    // TODO: Investigate and re-enable.
-    it.skip('opens a chat and load newer messages', async () => {
+    it('opens a chat and load newer messages', async () => {
         mockOpenReport(5, '5');
         mockGetNewerActions(5);
 
@@ -325,26 +323,43 @@ describe('Pagination', () => {
         });
         // ReportScreen relies on the onLayout event to receive updates from onyx.
         triggerListLayout();
+        await waitForBatchedUpdatesWithAct();
 
-        expect(getReportActions()).toHaveLength(5);
+        // Here we have 5 messages from the initial OpenReport and 5 from the initial GetNewerActions.
+        expect(getReportActions()).toHaveLength(10);
 
         // There is 1 extra call here because of the comment linking report.
         TestHelper.expectAPICommandToHaveBeenCalled('OpenReport', 2);
         TestHelper.expectAPICommandToHaveBeenCalledWith('OpenReport', 1, {reportID: REPORT_ID, reportActionID: '5'});
         TestHelper.expectAPICommandToHaveBeenCalled('GetOlderActions', 0);
-        TestHelper.expectAPICommandToHaveBeenCalled('GetNewerActions', 0);
+        TestHelper.expectAPICommandToHaveBeenCalledWith('GetNewerActions', 0, {reportID: REPORT_ID, reportActionID: '5'});
 
+        // Simulate the maintainVisibleContentPosition scroll adjustment, so it is now possible to scroll down more.
+        scrollToOffset(500);
         scrollToOffset(0);
         await waitForBatchedUpdatesWithAct();
 
         TestHelper.expectAPICommandToHaveBeenCalled('OpenReport', 2);
         TestHelper.expectAPICommandToHaveBeenCalled('GetOlderActions', 0);
-        TestHelper.expectAPICommandToHaveBeenCalled('GetNewerActions', 1);
-        TestHelper.expectAPICommandToHaveBeenCalledWith('GetNewerActions', 0, {reportID: REPORT_ID, reportActionID: '5'});
+        TestHelper.expectAPICommandToHaveBeenCalled('GetNewerActions', 2);
+        TestHelper.expectAPICommandToHaveBeenCalledWith('GetNewerActions', 1, {reportID: REPORT_ID, reportActionID: '10'});
+
+        // We now have 15 messages. 5 from the initial OpenReport and 10 from the 2 GetNewerActions calls.
+        expect(getReportActions()).toHaveLength(15);
 
+        // Simulate the backend returning no new messages to simulate reaching the start of the chat.
+        mockGetNewerActions(0);
+
+        scrollToOffset(500);
+        scrollToOffset(0);
         await waitForBatchedUpdatesWithAct();
 
-        // We now have 10 messages. 5 from the initial OpenReport and 5 from GetNewerActions.
-        expect(getReportActions()).toHaveLength(10);
+        TestHelper.expectAPICommandToHaveBeenCalled('OpenReport', 2);
+        TestHelper.expectAPICommandToHaveBeenCalled('GetOlderActions', 0);
+        TestHelper.expectAPICommandToHaveBeenCalled('GetNewerActions', 3);
+        TestHelper.expectAPICommandToHaveBeenCalledWith('GetNewerActions', 2, {reportID: REPORT_ID, reportActionID: '15'});
+
+        // We still have 15 messages. 5 from the initial OpenReport and 10 from the 2 GetNewerActions calls.
+        expect(getReportActions()).toHaveLength(15);
     });
 });