Dashboard fixes: staleness, toner, layout

frontend/src/components/dashboardCards.spec.js

@@ -2,6 +2,7 @@ import { describe, it, expect } from 'vitest'
 import {
   toApiPath, rows, mapMeta, mapLink, cardRows, metricValue,
   cardVisible, sortCards, permittedCards, renderableCards,
+  visibleRows, overflowCount,
 } from './dashboardCards'
 
 const failuresCard = {
@@ -77,6 +78,24 @@ describe('mapping a row', () => {
   })
 })
 
+describe('long lists', () => {
+  const many = (n) => ({
+    render: 'exceptions',
+    map: { title: 'hostname' },
+    _data: Array.from({ length: n }, (_v, i) => ({ hostname: `PC${i}` })),
+  })
+
+  it('shows at most five rows so one card cannot bury the rest', () => {
+    expect(visibleRows(many(40))).toHaveLength(5)
+    expect(overflowCount(many(40))).toBe(35)
+  })
+
+  it('does not claim an overflow when everything fits', () => {
+    expect(visibleRows(many(3))).toHaveLength(3)
+    expect(overflowCount(many(3))).toBe(0)
+  })
+})
+
 describe('empty handling', () => {
   it('hides a card with nothing to report by default', () => {
     // The whole point: a card saying "nothing wrong" daily trains people to