Fix KDateRange failing tests on prs opened on last day of the month

[LianaHarris360]

Description

This pull request fixes the failing KDateCalendar component tests that would occur on open pull requests on the last day of the month. This was fixed by setting dates manually in the tests. The KDateCalendar has also been updated to display the month of the property lastAllowedDate.

Issue addressed

Addresses #713

Changelog

• #718
  • Description: This pull request resolves failing KDateCalendar component tests that occurred on the last day of the month in open pull requests by setting dates manually in the tests. Additionally, the KDateCalendar is updated to show the month of the lastAllowedDate property.
  • Products impact: none
  • Addresses: KDateRange test failures: KDateRange test failure impacting month-end pull requests #713
  • Components: -
  • Breaking: no
  • Impacts a11y: -
  • Guidance: -

Testing checklist

• Contributor has fully tested the PR manually
• If there are any front-end changes, before/after screenshots are included
• Critical and brittle code paths are covered by unit tests
• The change is described in the changelog section above

Reviewer guidance

• Is the code clean and well-commented?
• Are there tests for this change?
• Are all UI components LTR and RTL compliant (if applicable)?
• Add other things to check for here

After review

• The changelog item has been pasted to the CHANGELOG.md

Comments

[AlexVelezLl]

I'm curious to know why 1 is subtracted from the active month. It means that the activeMonth will always be the month before the lastAllowedDate right? But if we are in January, the previous month would cause the year to also have to be reduced, but I see that activeYearStart is taken only from getFullYear.

[LianaHarris360]

This is because of how the Date() constructor in JavaScript sets the months. It uses an integer value to represent the month, beginning with 0 for January to 11 for December.

[AlexVelezLl]

Oh no, I meant what if the lastAllowedDate was for example new Date(2024, 0, 1), then activeMonth would be 11, but activeYearStart would be 2024, so the active date would be December 2024 instead of December 2023. But I looked at the code and I see that this activeYearStart value is updated in the created hook if this happens, so there is no problem.

Anyways I think we could avoid the ternary here, and the check in the created hook if we do something similar to get the previous month:

    data() {
      const previousMonth = new Date(this.lastAllowedDate);
      previousMonth.setMonth(lastAllowedDate.getMonth() - 1);
      return {
        ...,
        activeMonth: previousMonth.getMonth(),
        activeYearStart: previousMonth.getFullYear(),
      };
    },

But it is totally optional, although I think it would clarify the intention that activeMonth and activeYearStart refer to the previous month of the lastAllowedDate.

[AlexVelezLl]

lgtm! And code seems to be working even if lastAllowedDate is the last day of the month.