Added a round-trip test for formatting and parsing dates in all locales

scripts/test/locales.test.js

@@ -0,0 +1,34 @@
+/* eslint-env mocha */
+
+import path from 'path'
+import assert from 'power-assert'
+import Chance from 'chance'
+import format from '../../src/format'
+import parse from '../../src/parse'
+
+import listLocales from '../../scripts/_lib/listLocales'
+
+const chance = new Chance(42)
+
+listLocales().forEach(({ name, code }) => {
+  describe(`${name}`, () => {
+    chance.n(chance.date, 1).forEach(date => {
+      it(`parse(format(${date.toISOString()})) = ${date.toISOString()}`, () => {
+        const locale = require(path.join('..', '..', 'src', 'locale', code))
+        const formattedDate = format(
+          date,
+          locale.formatLong.date({ width: 'long' }),
+          { locale }
+        )
+
+        const parsedDate = parse(formattedDate, 'PP', date, { locale })
+        console.log(formattedDate, parsedDate)
+
+        assert.deepEqual(
+          parsedDate.toLocaleDateString(),
+          date.toLocaleDateString()
+        )
+      })
+    })
+  })
+})