test: add Japanese locale unit tests (#1280)

test/locale/ja.test.js

@@ -0,0 +1,45 @@
+import MockDate from 'mockdate'
+import moment from 'moment'
+import dayjs from '../../src'
+import relativeTime from '../../src/plugin/relativeTime'
+import '../../src/locale/ja'
+
+dayjs.extend(relativeTime)
+
+beforeEach(() => {
+  MockDate.set(new Date())
+})
+
+afterEach(() => {
+  MockDate.reset()
+})
+
+it('Finnish locale relative time in past and future', () => {
+  const cases = [
+    [1, 'd', '1日後'],
+    [-1, 'd', '1日前'],
+    [2, 'd', '2日後'],
+    [-2, 'd', '2日前'],
+    [10, 'd', '10日後'],
+    [-10, 'd', '10日前'],
+    [6, 'm', '6分後'],
+    [-6, 'm', '6分前'],
+    [5, 'h', '5時間後'],
+    [-5, 'h', '5時間前'],
+    [3, 'M', '3ヶ月後'],
+    [-3, 'M', '3ヶ月前'],
+    [4, 'y', '4年後'],
+    [-4, 'y', '4年前']
+  ]
+  cases.forEach((c) => {
+    expect(dayjs().add(c[0], c[1]).locale('ja').fromNow())
+      .toBe(c[2])
+    expect(dayjs().add(c[0], c[1]).locale('ja').fromNow())
+      .toBe(moment().add(c[0], c[1]).locale('ja').fromNow())
+  })
+  expect(dayjs().add(-10, 'd').locale('ja').fromNow(true))
+    .toBe('10日')
+  expect(dayjs().add(-10, 'd').locale('ja').fromNow(true))
+    .toBe(moment().add(-10, 'd').locale('ja').fromNow(true))
+})
+