fix: timezone plugin compatibility. Note: when extending dayjs with plugins, make sure to have utc and timeZone plugins AFTER our calendarSystems plugin

Author: amirhmoradi

Diff for: package.json

@@ -103,7 +103,8 @@
     "calendarSystems",
     "calendarUtils",
     "*.md",
-    "*.min.js"
+    "*.min.js",
+    "index.d.ts"
   ],
   "devDependencies": {
     "@babel/cli": "^7.21.5",

Diff for: src/index.js

@@ -6,7 +6,6 @@
  * 
  * This plugin allows Day.js to work with different calendar systems.
  */
-import CalendarSystemBase from "./calendarSystems/CalendarSystemBase";
 import GregoryCalendarSystem from "./calendarSystems/GregoryCalendarSystem";
 
 // The built-in calendar systems
@@ -30,6 +29,10 @@ export default (options, dayjsClass, dayjsFactory) => {
     }, {});
     // Create a new instance of the class with the given date:
     const newInstance = dayjsFactory(date, properties);
+    // Add the $x property (used for timezone) to the new instance:
+    if ("$x" in instance) {
+      newInstance.$x = instance.$x;
+    }
     if ("$C" in instance && instance.$C !== "gregory") {
       // If the calendar system is set, convert the date to the specified calendar system
       return newInstance.toCalendarSystem(instance.$C);

Diff for: test/daysInMonth.test.js

@@ -1,4 +1,7 @@
 import dayjs from "dayjs";
+import timeZone from "dayjs/plugin/timezone";
+//import toArray from "dayjs/plugin/toArray";
+import utc from "dayjs/plugin/utc";
 import calendarSystems from "../src/index";
 import GregoryCalendarSystem from "../src/calendarSystems/GregoryCalendarSystem";
 import PersianCalendarSystem from "../src/calendarSystems/PersianCalendarSystem";
@@ -8,6 +11,8 @@ describe("daysInMonth method with different calendar systems", () => {
     dayjs.extend(calendarSystems);
     dayjs.registerCalendarSystem("gregory", new GregoryCalendarSystem());
     dayjs.registerCalendarSystem("persian", new PersianCalendarSystem());
+    dayjs.extend(utc);
+    dayjs.extend(timeZone);
   });
 
   test("should return the correct number of days in a month for Gregorian calendar", () => {
@@ -19,10 +24,55 @@ describe("daysInMonth method with different calendar systems", () => {
   });
 
   test("should return the correct number of days in a month for Persian calendar", () => {
-    const dateInFarvardin = dayjs("2023-03-21").toCalendarSystem("persian");
+    // console.log("TEST_DAYS_IN_MONTH", 
+    // dayjs("2023-03-21").toDate().toLocaleString('en-US', { timeZone: "Europe/Paris" }), 
+    // dayjs("2023-03-21").toCalendarSystem("persian").toDate().toLocaleString('en-US', { timeZone: "Europe/Paris" }), 
+    // dayjs("2023-03-21").tz("Europe/Paris").toCalendarSystem("persian").toDate().toLocaleString('en-US', { timeZone: "Europe/Paris" })
+    // );
+    const dateInFarvardin = dayjs("2023-03-21").tz("Europe/Paris").toCalendarSystem("persian");
     const daysInFarvardin = dateInFarvardin.daysInMonth();
     expect(daysInFarvardin).toBe(31);
 
+    const dateInOrdibehesht = dayjs("2023-04-21").toCalendarSystem("persian");
+    const daysInOrdibehesht = dateInOrdibehesht.daysInMonth();
+    expect(daysInOrdibehesht).toBe(31);
+
+    const dateInKhordad = dayjs("2023-05-21").toCalendarSystem("persian");
+    const daysInKhordad = dateInKhordad.daysInMonth();
+    expect(daysInKhordad).toBe(31);
+
+    const dateInTir = dayjs("2023-06-21").toCalendarSystem("persian");
+    const daysInTir = dateInTir.daysInMonth();
+    expect(daysInTir).toBe(31);
+
+    const dateInMordad = dayjs("2023-07-21").toCalendarSystem("persian");
+    const daysInMordad = dateInMordad.daysInMonth();
+    expect(daysInMordad).toBe(31);
+
+    const dateInShahrivar = dayjs("2023-08-21").toCalendarSystem("persian");
+    const daysInShahrivar = dateInShahrivar.daysInMonth();
+    expect(daysInShahrivar).toBe(31);
+
+    const dateInMehr = dayjs("2023-09-23").toCalendarSystem("persian");
+    const daysInMehr = dateInMehr.daysInMonth();
+    expect(daysInMehr).toBe(30);
+
+    const dateInAban = dayjs("2023-10-21").toCalendarSystem("persian");
+    const daysInAban = dateInAban.daysInMonth();
+    expect(daysInAban).toBe(30);
+
+    const dateInAzar = dayjs("2023-11-21").toCalendarSystem("persian");
+    const daysInAzar = dateInAzar.daysInMonth();
+    expect(daysInAzar).toBe(30);
+
+    const dateInDey = dayjs("2023-12-21").tz("Europe/Paris").toCalendarSystem("persian");
+    const daysInDey = dateInDey.daysInMonth();
+    expect(daysInDey).toBe(30);
+
+    const dateInBahman = dayjs("2023-01-21").tz("Europe/Paris").toCalendarSystem("persian");
+    const daysInBahman = dateInBahman.daysInMonth();
+    expect(daysInBahman).toBe(30);
+    
     const dateInEsfand = dayjs("2024-02-20").toCalendarSystem("persian");
     const daysInEsfand = dateInEsfand.daysInMonth();
     expect(daysInEsfand).toBe(29); // Esfand in a leap year has 29 days