test(scroll-restoration): add massive scaling coverage (JhaSourav07#3006)

Author: mayank200529

app/components/ScrollRestoration.massive-scaling.test.tsx

@@ -0,0 +1,83 @@
+import { render } from '@testing-library/react';
+import { beforeEach, describe, expect, it, vi } from 'vitest';
+
+import ScrollRestoration from './ScrollRestoration';
+
+const mockUsePathname = vi.fn();
+
+vi.mock('next/navigation', () => ({
+  usePathname: () => mockUsePathname(),
+}));
+
+describe('ScrollRestoration massive scaling behavior', () => {
+  beforeEach(() => {
+    vi.clearAllMocks();
+    sessionStorage.clear();
+    mockUsePathname.mockReturnValue('/');
+    window.scrollTo = vi.fn();
+  });
+
+  it('renders repeatedly without crashing under high mount volume', () => {
+    expect(() => {
+      for (let index = 0; index < 100; index++) {
+        render(<ScrollRestoration />);
+      }
+    }).not.toThrow();
+  });
+
+  it('handles many stored scroll positions without breaking restoration', () => {
+    for (let index = 0; index < 500; index++) {
+      sessionStorage.setItem(`scroll-position-/page-${index}`, String(index));
+    }
+
+    mockUsePathname.mockReturnValue('/page-499');
+
+    render(<ScrollRestoration />);
+
+    expect(window.scrollTo).toHaveBeenCalledWith(0, 499);
+  });
+
+  it('stores scroll position correctly after many scroll events', () => {
+    render(<ScrollRestoration />);
+
+    for (let index = 0; index < 100; index++) {
+      Object.defineProperty(window, 'scrollY', {
+        value: index,
+        configurable: true,
+      });
+
+      window.dispatchEvent(new Event('scroll'));
+    }
+
+    expect(sessionStorage.getItem('scroll-position-/')).toBe('99');
+  });
+
+  it('keeps pathname-specific keys isolated at scale', () => {
+    for (let index = 0; index < 50; index++) {
+      mockUsePathname.mockReturnValue(`/dashboard-${index}`);
+
+      const { unmount } = render(<ScrollRestoration />);
+
+      Object.defineProperty(window, 'scrollY', {
+        value: index * 10,
+        configurable: true,
+      });
+
+      window.dispatchEvent(new Event('scroll'));
+      unmount();
+    }
+
+    expect(sessionStorage.getItem('scroll-position-/dashboard-0')).toBe('0');
+    expect(sessionStorage.getItem('scroll-position-/dashboard-49')).toBe('490');
+  });
+  it('removes scroll listener safely after many unmount cycles', () => {
+    const removeEventListenerSpy = vi.spyOn(window, 'removeEventListener');
+
+    for (let index = 0; index < 25; index++) {
+      const { unmount } = render(<ScrollRestoration />);
+      unmount();
+    }
+
+    expect(removeEventListenerSpy).toHaveBeenCalledTimes(25);
+  });
+});