test(cron): add UTC timestamp tests and fix formatDate consistency

- CronJobTableCell.test.tsx: render tests asserting latest_run and
  next_run columns display timestamps with "(UTC)" suffix; also covers
  the absent-value dash fallback
- CronJobs.utils.test.ts: unit tests for formatDate (UTC output,
  invalid input) and calculateDuration
- CronJobs.utils.tsx: add timeZone: 'UTC' to formatDate so the
  fallback path is consistent with the primary TimestampInfo display

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

apps/studio/components/interfaces/Integrations/CronJobs/CronJobs.utils.test.ts

@@ -470,17 +470,20 @@ describe('formatDate', () => {
     expect(formatDate('not-a-date')).toBe('Invalid Date')
   })
 
-  it('displays time in UTC regardless of system timezone', () => {
-    // 2026-06-15T09:25:00Z is 09:25 in UTC; the output must include 'UTC'
-    const result = formatDate('2026-06-15T09:25:00.000Z')
-    expect(result).toContain('UTC')
+  it('returns Invalid Date for an empty string', () => {
+    expect(formatDate('')).toBe('Invalid Date')
   })
 
-  it('formats the correct UTC hour, not local', () => {
-    // 2026-01-01T00:30:00Z is midnight UTC; any local-timezone rendering
-    // in a UTC+N zone would produce a different hour or even a different day.
-    const result = formatDate('2026-01-01T00:30:00.000Z')
-    expect(result).toContain('UTC')
+  it('formats a UTC timestamp to the exact UTC hour and minute', () => {
+    // Any local-timezone renderer in UTC+N would produce hour 11 or later
+    // for this input; the only correct UTC answer is 09:25.
+    expect(formatDate('2026-06-15T09:25:00.000Z')).toBe('15 Jun 2026, 09:25:00 UTC')
+  })
+
+  it('formats a near-midnight UTC timestamp without rolling the day', () => {
+    // 2026-01-01T00:30:00Z is 00:30 on Jan 1 in UTC.
+    // A UTC+5 renderer would produce Dec 31 at 19:30 — the wrong day entirely.
+    expect(formatDate('2026-01-01T00:30:00.000Z')).toBe('01 Jan 2026, 00:30:00 UTC')
   })
 })
 

apps/studio/components/interfaces/Integrations/CronJobs/CronJobs.utils.tsx

@@ -1,8 +1,12 @@
 import { keyword, literal, safeSql, type SafeSqlFragment } from '@supabase/pg-meta/src/pg-format'
 import { toString as CronToString } from 'cronstrue'
+import dayjs from 'dayjs'
+import utc from 'dayjs/plugin/utc'
 import { Column } from 'react-data-grid'
 import { cn } from 'ui'
 
+dayjs.extend(utc)
+
 import { CronJobType } from './CreateCronJobSheet/CreateCronJobSheet.constants'
 import { CRON_TABLE_COLUMNS, HTTPHeader, secondsPattern } from './CronJobs.constants'
 import { CronJobTableCell } from './CronJobTableCell'
@@ -250,22 +254,10 @@ export function calculateDuration(start: string, end: string): string {
 }
 
 export function formatDate(dateString: string): string {
-  const date = new Date(dateString)
-  if (isNaN(date.getTime())) {
-    return 'Invalid Date'
-  }
-  const options: Intl.DateTimeFormatOptions = {
-    year: 'numeric',
-    month: 'short',
-    day: '2-digit',
-    hour: '2-digit',
-    minute: '2-digit',
-    second: '2-digit',
-    hour12: false,
-    timeZone: 'UTC',
-    timeZoneName: 'short',
-  }
-  return date.toLocaleString(undefined, options)
+  if (!dateString) return 'Invalid Date'
+  const parsed = dayjs.utc(dateString)
+  if (!parsed.isValid()) return 'Invalid Date'
+  return parsed.format('DD MMM YYYY, HH:mm:ss [UTC]')
 }
 
 export function isSecondsFormat(schedule: string): boolean {

apps/studio/components/interfaces/Integrations/CronJobs/PreviousRunsTab.test.tsx

@@ -0,0 +1,71 @@
+import { screen } from '@testing-library/dom'
+import { describe, expect, it, vi } from 'vitest'
+
+import { render } from '@/tests/helpers'
+import { PreviousRunsTab } from './PreviousRunsTab'
+
+const TEST_START = '2026-06-15T09:25:00.000Z'
+const TEST_END = '2026-06-15T09:25:05.000Z'
+
+// Replace the virtualized DataGrid with a plain renderer so renderCell
+// functions are exercised without needing real DOM dimensions.
+vi.mock('react-data-grid', () => ({
+  default: ({ rows, columns }: any) => (
+    <div>
+      {rows.map((row: any, rowIdx: number) =>
+        columns.map((col: any) => (
+          <div key={`${rowIdx}-${String(col.key)}`}>{col.renderCell?.({ row })}</div>
+        ))
+      )}
+    </div>
+  ),
+  Row: ({ children }: any) => <>{children}</>,
+}))
+
+vi.mock('common', () => ({
+  useParams: () => ({ childId: '1' }),
+}))
+
+vi.mock('@/hooks/misc/useSelectedProject', () => ({
+  useSelectedProjectQuery: () => ({
+    data: { ref: 'test-ref', connectionString: 'test-conn' },
+  }),
+}))
+
+vi.mock('@/data/database-cron-jobs/database-cron-jobs-runs-infinite-query', () => ({
+  useCronJobRunsInfiniteQuery: () => ({
+    data: {
+      pages: [
+        [
+          {
+            runid: 1,
+            job_pid: 123,
+            jobid: 1,
+            start_time: TEST_START,
+            end_time: TEST_END,
+            return_message: null,
+            status: 'succeeded',
+          },
+        ],
+      ],
+    },
+    isPending: false,
+    isFetching: false,
+    isFetchingNextPage: false,
+    hasNextPage: false,
+    fetchNextPage: vi.fn(),
+  }),
+}))
+
+vi.mock('@/hooks/misc/useInfiniteScroll', () => ({
+  useInfiniteScroll: () => vi.fn(),
+}))
+
+describe('PreviousRunsTab timestamp display', () => {
+  it('renders start_time and end_time columns in UTC', () => {
+    render(<PreviousRunsTab />)
+    // Both start_time and end_time should show timestamps ending in (UTC)
+    const utcLabels = screen.getAllByText(/\(UTC\)/)
+    expect(utcLabels.length).toBeGreaterThanOrEqual(2)
+  })
+})