Split up tests, use date-fns as helpers

src/lib/strings/__tests__/time.test.ts

@@ -0,0 +1,99 @@
+import {describe, expect, it} from '@jest/globals'
+import {addDays, subDays, subHours, subMinutes, subSeconds} from 'date-fns'
+
+import {dateDiff} from '../time'
+
+const base = new Date('2024-06-17T00:00:00Z')
+
+describe('dateDiff', () => {
+  it(`works with numbers`, () => {
+    expect(dateDiff(subDays(base, 3), Number(base))).toEqual('3d')
+  })
+  it(`works with strings`, () => {
+    expect(dateDiff(subDays(base, 3), base.toString())).toEqual('3d')
+  })
+  it(`works with dates`, () => {
+    expect(dateDiff(subDays(base, 3), base)).toEqual('3d')
+  })
+
+  it(`equal values return now`, () => {
+    expect(dateDiff(base, base)).toEqual('now')
+  })
+  it(`future dates return now`, () => {
+    expect(dateDiff(addDays(base, 3), base)).toEqual('now')
+  })
+
+  it(`values < 5 seconds ago return now`, () => {
+    const then = subSeconds(base, 4)
+    expect(dateDiff(then, base)).toEqual('now')
+  })
+  it(`values >= 5 seconds ago return seconds`, () => {
+    const then = subSeconds(base, 5)
+    expect(dateDiff(then, base)).toEqual('5s')
+  })
+
+  it(`values < 1 min return seconds`, () => {
+    const then = subSeconds(base, 59)
+    expect(dateDiff(then, base)).toEqual('59s')
+  })
+  it(`values >= 1 min return minutes`, () => {
+    const then = subSeconds(base, 60)
+    expect(dateDiff(then, base)).toEqual('1m')
+  })
+  it(`minutes round down`, () => {
+    const then = subSeconds(base, 119)
+    expect(dateDiff(then, base)).toEqual('1m')
+  })
+
+  it(`values < 1 hour return minutes`, () => {
+    const then = subMinutes(base, 59)
+    expect(dateDiff(then, base)).toEqual('59m')
+  })
+  it(`values >= 1 hour return hours`, () => {
+    const then = subMinutes(base, 60)
+    expect(dateDiff(then, base)).toEqual('1h')
+  })
+  it(`hours round down`, () => {
+    const then = subMinutes(base, 119)
+    expect(dateDiff(then, base)).toEqual('1h')
+  })
+
+  it(`values < 1 day return hours`, () => {
+    const then = subHours(base, 23)
+    expect(dateDiff(then, base)).toEqual('23h')
+  })
+  it(`values >= 1 day return days`, () => {
+    const then = subHours(base, 24)
+    expect(dateDiff(then, base)).toEqual('1d')
+  })
+  it(`days round down`, () => {
+    const then = subHours(base, 47)
+    expect(dateDiff(then, base)).toEqual('1d')
+  })
+
+  it(`values < 30 days return days`, () => {
+    const then = subDays(base, 29)
+    expect(dateDiff(then, base)).toEqual('29d')
+  })
+  it(`values >= 30 days return months`, () => {
+    const then = subDays(base, 30)
+    expect(dateDiff(then, base)).toEqual('1mo')
+  })
+  it(`months round down`, () => {
+    const then = subDays(base, 59)
+    expect(dateDiff(then, base)).toEqual('1mo')
+  })
+  it(`values are rounded by increments of 30`, () => {
+    const then = subDays(base, 61)
+    expect(dateDiff(then, base)).toEqual('2mo')
+  })
+
+  it(`values < 360 days return months`, () => {
+    const then = subDays(base, 359)
+    expect(dateDiff(then, base)).toEqual('11mo')
+  })
+  it(`values >= 360 days return the earlier value`, () => {
+    const then = subDays(base, 361)
+    expect(dateDiff(then, base)).toEqual(then.toLocaleDateString())
+  })
+})

src/lib/strings/time.ts

@@ -1,3 +1,5 @@
+import {differenceInSeconds} from 'date-fns'
+
 export function ago(date: number | string | Date): string {
   return dateDiff(date, Date.now())
 }
@@ -7,28 +9,17 @@ const MINUTE = 60
 const HOUR = MINUTE * 60
 const DAY = HOUR * 24
 const MONTH_30 = DAY * 30
-/** Returns the difference between date1 and date2 in full seconds, minutes, hours etc. All month are considered exactly 30 days. Assuming that date1 <= date2. Differences >= 360 days are returned as the "M/D/YYYY" string. */
+
+/**
+ * Returns the difference between date1 and date2 in full seconds, minutes,
+ * hours etc. All month are considered exactly 30 days. Assuming that date1 <=
+ * date2. Differences >= 360 days are returned as the "M/D/YYYY" string
+ */
 export function dateDiff(
-  date1: number | string | Date,
-  date2: number | string | Date,
+  earlier: number | string | Date,
+  later: number | string | Date,
 ): string {
-  let ts1: number
-  if (typeof date1 === 'string') {
-    ts1 = Number(new Date(date1))
-  } else if (date1 instanceof Date) {
-    ts1 = Number(date1)
-  } else {
-    ts1 = date1
-  }
-  let ts2: number
-  if (typeof date2 === 'string') {
-    ts2 = Number(new Date(date2))
-  } else if (date2 instanceof Date) {
-    ts2 = Number(date2)
-  } else {
-    ts2 = date2
-  }
-  const diffSeconds = Math.floor((ts2 - ts1) / 1e3)
+  const diffSeconds = differenceInSeconds(new Date(later), new Date(earlier))
   if (diffSeconds < NOW) {
     return `now`
   } else if (diffSeconds < MINUTE) {
@@ -44,7 +35,7 @@ export function dateDiff(
     if (diffMonths30 < 12) {
       return `${diffMonths30}mo`
     } else {
-      return new Date(ts1).toLocaleDateString()
+      return new Date(earlier).toLocaleDateString()
     }
   }
 }