PowerPoint: fix errors when reading text formatting and hyperlinks

[ChristosBouronikos]

Link to issue number:

None. These are coding errors in appModules/powerpnt.py, found while reviewing the PowerPoint app module.

Summary of the issue:

Several code paths in the PowerPoint text frame text info cannot work as written:

• _getFormatFieldAndOffsets calls _getCurrentRun(self), passing the text info where a character offset is expected. Finding the formatting run for a position therefore raises a TypeError instead of returning a run.
• When no run is found, the fallback characters(offset + 1) has no length, so it covers the rest of the story instead of the single character at the offset.
• _getPptTextRange raises ValueError(..., stack_info=True). ValueError does not accept keyword arguments, so the intended ValueError is replaced by a TypeError.
• _getLinkDataAtCaretPosition builds the result with textInfos._LinkData, which does not exist (the class is imported from utils.urlUtils), and it dereferences the formatting run without checking whether one was found.

Description of user facing changes:

In Microsoft PowerPoint, formatting information and the link at the caret can be reported without NVDA raising an error.

Description of developer facing changes:

None.

Description of development approach:

• Pass the offset to _getCurrentRun, and request a single character when falling back to characters().
• Raise a plain ValueError. The message already contains the start and end values.
• Use the imported _LinkData and return None when there is no formatting run at the caret.

Testing strategy:

• Added tests/unit/test_appModules/test_powerpnt_textFrame.py. The tests cover finding the run from an offset, the single-character fallback, the ValueError, a link lookup without a run, and a link lookup that returns the shared _LinkData type. Without the change, every test fails.
• The new tests and the lint checks (ruff, add-trailing-comma) pass locally using stand-ins for the Windows modules. The complete unit test suite also passes on Windows (Python 3.13, x64), run on a build of this branch in a private repository.
• Manual testing in Microsoft PowerPoint is still outstanding. This PR is a draft until it has been done.

Known issues with pull request:

None known. The change log entry is deliberately generic because there is no issue to reference.

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.

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