fix: fix utc plugin diff bug in DST (#1171)

iamkun · iamkun · commit f8da3fe7e50c · 2020-10-30T11:10:51.000+08:00
fix #1097, fix #1021
diff --git a/src/plugin/utc/index.js b/src/plugin/utc/index.js
@@ -112,6 +112,9 @@ export default (option, Dayjs, dayjs) => {
   }
   const oldDiff = proto.diff
   proto.diff = function (input, units, float) {
+    if (this.$u === input.$u) {
+      return oldDiff.call(this, input, units, float)
+    }
     const localThis = this.local()
     const localInput = dayjs(input).local()
     return oldDiff.call(localThis, localInput, units, float)
diff --git a/test/timezone.test.js b/test/timezone.test.js
@@ -62,3 +62,11 @@ it('UTC and utcOffset', () => {
   expect(moment.utc(test2).utcOffset(-60).format())
     .toBe(dayjs.utc(test2).utcOffset(-60).format())
 })
+
+it('UTC diff in DST', () => {
+  // DST till 2020-10-25
+  const day1 = dayjs.utc('20201023') // in DST
+  const day2 = dayjs.utc('20201026')
+  expect(day1.diff(day2, 'd'))
+    .toBe(-3)
+})
