Fix: Date-related test failures due to UTC/local timezone mismatch Issue

[Han5991]

Issue

Two test files were failing due to timezone-related issues:

1. packages/@mantine/dates/src/components/Month/get-date-in-tab-order/get-date-in-tab-order.test.ts

   • Test case: returns current day
   • Expected: "2025-05-22" (UTC)
   • Received: "2025-05-23" (local KST)

2. packages/@mantine/dates/src/components/Day/Day.test.tsx

   • Test case: adds data-today attribute if date is the same as today
   • Failed to find expected data-today attribute

Root Cause

The tests were using new Date().toISOString().split('T')[0] which returns dates in UTC. This caused failures when the local date (e.g., KST, UTC+9) was different from the UTC date. For example, when it's May 23 in KST, it's still May 22 in UTC.

Solution

1. In get-date-in-tab-order.test.ts:

   • Updated the returns current day test to use dayjs().format('YYYY-MM-DD') for getting the current local date
   • Aligned the month parameter with the local date

2. In Day.test.tsx:

   • Added dayjs import
   • Updated the test to use dayjs().format('YYYY-MM-DD') when passing the date prop to the Day component

3. Code Style:

   • Ran Prettier to maintain consistent code formatting

Testing

• All tests in both files now pass successfully
• The components now correctly handle local dates in tests

Additional Notes

When writing tests that involve dates, it's important to be explicit about timezones. Using dayjs() without parameters ensures we're working with the local timezone, which is typically what we want for date component tests.

[rtivital]

Thanks!