Spin Button Date Picker: Fix unreliable date math test

[spectranaut]

When you get towards the end of the month and try to add a month, Javascript Date objects start to do unexpected things. This is causing failures in the CI for all regression tests run today. This is the issue:

let date = new Date('10/31/2020'); 
date.setMonth(date.getMonth + 1);

The second line increases the date by one month, resulting in date being December 1st, 2020, because there is no November 31st.

The fix is to put the day of the month to the 1st using date.setDate(1) before doing any math, because all months have the 1st of the month.

[github-actions]

Regression test coverage:

Examples without any regression tests:

• dialog-modal/alertdialog.html

Examples missing some regression tests:

• dialog-modal/datepicker-dialog.html:
  • textbox-aria-describedby
• menu-button/menu-button-actions-active-descendant.html:
  • menu-up-arrow
  • menu-down-arrow
  • menu-character
• toolbar/toolbar.html:
  • toolbar-tab
  • toolbar-right-arrow
  • toolbar-left-arrow
  • toolbar-home
  • toolbar-end
  • toolbar-toggle-esc
  • toolbar-toggle-enter-or-space
  • toolbar-radio-enter-or-space
  • toolbar-radio-down-arrow
  • toolbar-radio-up-arrow
  • toolbar-button-enter-or-space
  • toolbar-menubutton-enter-or-space-or-down-or-up
  • toolbar-menu-enter-or-space
  • toolbar-menu-down-arrow
  • toolbar-menu-up-arrow
  • toolbar-menu-escape
  • toolbar-spinbutton-down-arrow
  • toolbar-spinbutton-up-arrow
  • toolbar-spinbutton-page-down
  • toolbar-spinbutton-page-up
  • toolbar-checkbox-space
  • toolbar-link-enter-or-space
  • toolbar-spinbutton-role

Example pages with Keyboard or Attribute table rows that do not have data-test-ids:

• dialog-modal/alertdialog.html
  • "Keyboard Support" table(s):
    • Tab
    • Shift + Tab
    • Escape
    • Command + S
    • Control + S
  • "Attributes" table(s):
    • alertdialog
    • aria-labelledby=IDREF
    • aria-describedby=IDREF
    • aria-modal=true
    • alert

SUMMARY:

55 example pages found.
1 example pages have no regression tests.
3 example pages are missing approximately 27 out of approximately 780 tests.

ERROR - missing tests:

Please write missing tests for this report to pass.

[carmacleod]

+1
Makes sense.
Thanks @spectranaut !

[mcking65]

@spectranaut
Seems like we now have a problem with arrow key testing on day spinner

[nschonni]

Is this part still needed?