Update how our util functions round numbers (#1865)

* Use toFixed to handle rounding

* more precise comment

* Round it inline as well, just to be sure

Author: charliepark

app/pages/system/UtilizationPage.tsx

@@ -24,7 +24,7 @@ import {
   Table,
   Tabs,
 } from '@oxide/ui'
-import { bytesToGiB, bytesToTiB } from '@oxide/util'
+import { bytesToGiB, bytesToTiB, round } from '@oxide/util'
 
 import { CapacityBars } from 'app/components/CapacityBars'
 import { useDateTimeRangePicker } from 'app/components/form'
@@ -254,7 +254,8 @@ const AvailableCell = ({
   return (
     <div className="flex w-full items-center justify-between">
       <div>
-        {allocated - provisioned} {unit && <span className="text-tertiary">{unit}</span>}
+        {round(allocated - provisioned, 2)}
+        {unit && <span className="text-tertiary"> {unit}</span>}
       </div>
       {/* We only show the ResourceMeter if the percent crosses the warning threshold (66%) */}
       {usagePercent > 66 && (

app/test/e2e/utilization.e2e.ts

@@ -21,13 +21,13 @@ test.describe('System utilization', () => {
 
     const table = page.getByRole('table')
     await expectRowVisible(table, {
-      CPU: '20 ',
+      CPU: '20',
       Storage: '2.7 TiB',
       Memory: '66 GiB',
       Silo: 'maze-war',
     })
     await expectRowVisible(table, {
-      CPU: '26 ',
+      CPU: '26',
       Storage: '7 TiB',
       Memory: '350 GiB',
       Silo: 'myriad',

libs/util/math.spec.ts

@@ -16,6 +16,7 @@ it('rounds properly', () => {
   expect(round(123.456, 2)).toEqual(123.46)
   expect(round(123.456, 3)).toEqual(123.456)
   expect(round(123.456, 4)).toEqual(123.456) // trailing zeros are culled
+  expect(round(123.0001, 3)).toEqual(123) // period is culled if decimals are all zeros
   expect(round(1.9, 0)).toEqual(2)
   expect(round(1.9, 1)).toEqual(1.9)
   expect(round(5 / 2, 2)).toEqual(2.5) // math expressions are resolved

libs/util/math.ts

@@ -16,6 +16,5 @@ export function splitDecimal(value: number) {
 }
 
 export function round(num: number, digits: number) {
-  const pow10 = Math.pow(10, digits)
-  return Math.round((num + Number.EPSILON) * pow10) / pow10
+  return Number(num.toFixed(digits))
 }