Scheduler: T1311967 — Error occurs when dateCellRender is specified and switching between pages (#31721)

Author: sjbur

packages/devextreme-react/src/core/__tests__/integration/scheduler.test.tsx

@@ -0,0 +1,63 @@
+import * as testingLib from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+import * as React from 'react';
+import { Scheduler } from '../../../scheduler';
+
+describe('Scheduler component', () => {
+    beforeEach(() => {
+        jest.useRealTimers();
+    });
+
+    afterEach(() => {
+        testingLib.cleanup();
+        jest.useFakeTimers();
+    });
+
+    it('T1311967: re-renders dateCellRender content after navigation', async () => {
+        const currentDate = new Date(2025, 2, 28);
+        const data = [
+            {
+                text: 'Test Appointment',
+                startDate: new Date('2025-03-29T10:00:00'),
+                endDate: new Date('2025-03-29T11:00:00'),
+            },
+        ];
+
+        const user = userEvent.setup({ delay: null });
+
+        const dateCellRender = (cellData: any) => {
+            const date = new Date(cellData.date);
+            return <div className='custom-cell-marker'>Day {date.getDate()}</div>;
+        };
+
+        testingLib.render(
+            <Scheduler
+                timeZone="America/Los_Angeles"
+                dataSource={data}
+                defaultCurrentView="week"
+                defaultCurrentDate={currentDate}
+                dateCellRender={dateCellRender}
+                startDayHour={9}
+            />,
+        );
+
+        await testingLib.waitFor(() => {
+            const cells = document.querySelectorAll('.custom-cell-marker');
+            const hasMarchDates = Array.from(cells).some((cell) => cell.textContent?.includes('Day 28') ?? cell.textContent?.includes('Day 29'));
+            expect(hasMarchDates).toBe(true);
+        });
+
+        const nextButton = await testingLib.waitFor(() => {
+            const btn = document.querySelector('[aria-label="Next page"]') as HTMLElement;
+            expect(btn).toBeDefined();
+            return btn;
+        });
+        await user.click(nextButton);
+
+        await testingLib.waitFor(() => {
+            const cells = document.querySelectorAll('.custom-cell-marker');
+            const hasAprilDates = Array.from(cells).some((cell) => cell.textContent?.includes('Day 4') ?? cell.textContent?.includes('Day 5'));
+            expect(hasAprilDates).toBe(true);
+        });
+    });
+});