test: add dst test

package.json

@@ -6,6 +6,8 @@
   "types": "index.d.ts",
   "scripts": {
     "test": "jest",
+    "test-dst": "TZ=Pacific/Auckland npm run dst-test && TZ=Europe/London npm run dst-test && npm run dst-test",
+    "dst-test": "jest test/dst.test --coverage=false",
     "lint": "./node_modules/.bin/eslint src/* test/* build/*",
     "build": "cross-env BABEL_ENV=build node build && npm run size",
     "sauce": "npx karma start karma.sauce.conf.js",

test/dst.test.js

@@ -0,0 +1,21 @@
+import moment from 'moment'
+import MockDate from 'mockdate'
+import dayjs from '../src'
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('Add Time days (DST)', () => {
+  // change timezone before running test
+  // New Zealand (-720)
+  expect(dayjs('2018-04-01').add(1, 'd').format()).toBe(moment('2018-04-01').add(1, 'd').format())
+  expect(dayjs('2018-03-28').add(1, 'w').format()).toBe(moment('2018-03-28').add(1, 'w').format())
+  // London (-60)
+  expect(dayjs('2018-10-28').add(1, 'd').format()).toBe(moment('2018-10-28').add(1, 'd').format())
+  expect(dayjs('2018-10-26').add(1, 'w').format()).toBe(moment('2018-10-26').add(1, 'w').format())
+})

test/manipulate.test.js

@@ -52,13 +52,3 @@ it('Add Time days', () => {
 it('Subtract Time days', () => {
   expect(dayjs().subtract(1, 'days').valueOf()).toBe(moment().subtract(1, 'days').valueOf())
 })
-
-it('Add Time days (DST)', () => {
-  // change timezone before running test
-  // New Zealand (-720)
-  expect(dayjs('2018-04-01').add(1, 'd').format()).toBe(moment('2018-04-01').add(1, 'd').format())
-  expect(dayjs('2018-03-28').add(1, 'w').format()).toBe(moment('2018-03-28').add(1, 'w').format())
-  // London (-60)
-  expect(dayjs('2018-10-28').add(1, 'd').format()).toBe(moment('2018-10-28').add(1, 'd').format())
-  expect(dayjs('2018-10-26').add(1, 'w').format()).toBe(moment('2018-10-26').add(1, 'w').format())
-})