feat(jest): Add timezone unit test (#1615)

utilities/Timezone.test.ts

@@ -0,0 +1,26 @@
+import * as Timezone from './Timezone'
+
+describe('init', () => {
+  test('getTimezoneDropdowns', () => {
+    const result = Timezone.getTimezoneDropdowns()
+    const nonDaylightTimezone = result.find((obj) => {
+      return obj.alternativeName === 'Singapore Time'
+    })
+
+    expect(result.length).not.toBeNull()
+    expect(result.length).toBeGreaterThan(0)
+    expect(nonDaylightTimezone.currentTimeFormat).toEqual(
+      '+08:00 Singapore Time - Singapore, Woodlands, Marine Parade',
+    ) // Make sure that the nonDaylightTimezone exists.
+  })
+  test('getUtfOffsetInMins for an existing timezone', () => {
+    const result = Timezone.getUtfOffsetInMins('Asia/Singapore')
+
+    expect(result).toBe(480)
+  })
+  test('getUtfOffsetInMins for a non existing timezone', () => {
+    const result = Timezone.getUtfOffsetInMins('Asia/Singapura')
+
+    expect(result).toBeNull()
+  })
+})