Improve formatDate, add more unit tests

packages/ripple-ui-core/src/lib/helpers.test.ts

@@ -0,0 +1,45 @@
+import { expect, describe, it } from '@jest/globals'
+
+import { formatDate, distanceAsPercentage } from './helpers.js'
+
+describe('Formatting a date', () => {
+  const raw = '2024-08-02T09:00:00+1000'
+
+  it('formats a date', () => {
+    expect(formatDate(raw)).toEqual('2 Aug 2024')
+  })
+
+  it('accepts custom date options', () => {
+    expect(
+      formatDate(raw, { day: 'numeric', month: 'short', year: '2-digit' })
+    ).toEqual('2 Aug 24')
+  })
+
+  it('accepts custom date options with a non-default tz', () => {
+    expect(
+      formatDate(raw, {
+        dateStyle: 'medium',
+        timeZone: 'Japan',
+        timeStyle: 'short'
+      })
+    ).toEqual('2 Aug 2024, 8:00 am')
+  })
+})
+
+describe('Transform distance to percentage', () => {
+  it('transforms a simple 100-scale', () => {
+    expect(distanceAsPercentage(35, 100)).toEqual(35)
+  })
+
+  it('transforms a point above ceil', () => {
+    expect(distanceAsPercentage(110, 100)).toEqual(100)
+  })
+
+  it('transforms a point below floor', () => {
+    expect(distanceAsPercentage(-80, 100)).toEqual(0)
+  })
+
+  it('transforms a complex scale', () => {
+    expect(distanceAsPercentage(29, 76)).toEqual(38.16)
+  })
+})

packages/ripple-ui-core/src/lib/helpers.ts

@@ -11,15 +11,24 @@ export const distanceAsPercentage = (point: number, total: number): number => {
 
 export const formatDate = (
   value: string | number | Date,
-  options: Intl.DateTimeFormatOptions = {}
+  options: Intl.DateTimeFormatOptions | undefined = undefined
 ): string => {
   const date = new Date(value)
 
-  const defaultOptions: Intl.DateTimeFormatOptions = { dateStyle: 'medium', timeZone: 'Australia/Melbourne' }
+  const defaultOptions: Intl.DateTimeFormatOptions = {
+    dateStyle: 'medium',
+    timeZone: 'Australia/Melbourne'
+  }
 
-  options = { ...defaultOptions, ...options }
+  // Set default TZ
+  if (options && !options.timeZone) {
+    options.timeZone = 'Australia/Melbourne'
+  }
 
-  return new Intl.DateTimeFormat('en-AU', options).format(date)
+  return new Intl.DateTimeFormat(
+    'en-AU',
+    options ? options : defaultOptions
+  ).format(date)
 }
 
 export { formatDateRange } from './formatDateRange'