test: add unit coverage for findings selected-row virtualizer scrolling (#1408)

frontend/testing/unit/pages/Findings.test.tsx

@@ -25,6 +25,22 @@ vi.mock('../../../src/utils/date', async (importOriginal: any) => {
   }
 })
 
+const mockScrollToIndex = vi.fn()
+
+vi.mock('@tanstack/react-virtual', async (importOriginal) => {
+  const actual = await importOriginal<any>()
+  return {
+    ...actual,
+    useVirtualizer: (options: any) => {
+      const virtualizer = actual.useVirtualizer(options)
+      return {
+        ...virtualizer,
+        scrollToIndex: mockScrollToIndex,
+      }
+    },
+  }
+})
+
 // @tanstack/react-virtual needs ResizeObserver + scrollHeight in jsdom
 if (typeof global.ResizeObserver === 'undefined') {
   global.ResizeObserver = class ResizeObserver {
@@ -34,7 +50,6 @@ if (typeof global.ResizeObserver === 'undefined') {
   } as any
 }
 
-
 Object.defineProperty(HTMLElement.prototype, 'scrollHeight', { configurable: true, value: 800 })
 Object.defineProperty(HTMLElement.prototype, 'offsetHeight', { configurable: true, value: 600 })
 
@@ -451,3 +466,72 @@ describe('Findings — severity legend help affordance', () => {
     )
   })
 })
+
+describe('Findings — virtualizer scrolling', () => {
+  beforeEach(() => {
+    vi.clearAllMocks()
+    localStorage.clear()
+  })
+
+  it('changing the selected finding triggers the expected scroll call', async () => {
+    const findings = [
+      makeFinding({ id: 'f1', title: 'Finding Alpha', severity: 'critical' }),
+      makeFinding({ id: 'f2', title: 'Finding Beta', severity: 'high' }),
+      makeFinding({ id: 'f3', title: 'Finding Gamma', severity: 'medium' }),
+    ]
+    vi.mocked(getFindings).mockResolvedValue({ findings })
+
+    render(<Findings />)
+    await waitFor(() => expect(screen.queryByText('Synchronizing findings feed...')).not.toBeInTheDocument())
+
+    // Clear initial scroll call on mount
+    mockScrollToIndex.mockClear()
+
+    // Click Finding Beta to select it
+    const betaOption = await screen.findByRole('option', { name: /Finding Beta/i })
+    await userEvent.click(betaOption)
+
+    // Assert it called scrollToIndex with correct index (1)
+    expect(mockScrollToIndex).toHaveBeenCalledWith(1, { align: 'auto', behavior: 'smooth' })
+  })
+
+  it('filtering/sorting does not scroll to stale indexes', async () => {
+    const findings = [
+      makeFinding({ id: 'f1', title: 'Finding Alpha', severity: 'critical' }),
+      makeFinding({ id: 'f2', title: 'Finding Beta', severity: 'high' }),
+      makeFinding({ id: 'f3', title: 'Finding Gamma', severity: 'medium' }),
+    ]
+    vi.mocked(getFindings).mockResolvedValue({ findings })
+
+    render(<Findings />)
+    await waitFor(() => expect(screen.queryByText('Synchronizing findings feed...')).not.toBeInTheDocument())
+
+    // Select Beta (triggers scroll) and then clear mocks
+    const betaOption = await screen.findByRole('option', { name: /Finding Beta/i })
+    await userEvent.click(betaOption)
+    expect(mockScrollToIndex).toHaveBeenCalled()
+    mockScrollToIndex.mockClear()
+
+    // Filter using search query that includes Beta
+    const searchInput = screen.getByPlaceholderText(/Title, target, CVE/i)
+    await userEvent.type(searchInput, 'Beta')
+
+    // Expect no scrollToIndex call because selectedFindingId did not change
+    expect(mockScrollToIndex).not.toHaveBeenCalled()
+
+    // Clear search query
+    await userEvent.clear(searchInput)
+    expect(mockScrollToIndex).not.toHaveBeenCalled()
+
+    // Change sorting mode (while Beta remains visible/selected)
+    const selects = screen.getAllByRole('combobox')
+    const sortSelect = selects.find((s) =>
+      Array.from(s.querySelectorAll('option')).some((o) => /Newest First/i.test(o.textContent || '')),
+    )
+    expect(sortSelect).toBeDefined()
+    await userEvent.selectOptions(sortSelect!, 'newest')
+
+    // Expect no scrollToIndex call
+    expect(mockScrollToIndex).not.toHaveBeenCalled()
+  })
+})