Fix: Issue with single character formatting in the toggle style button .

[shivansh00011]

Description

Fixed the issue with single character formatting in the toggle style button. Previously, when formatting a single character (e.g., making it bold), the toolbar state was incorrectly affected, causing subsequent text to be formatted by default. This was due to using the incorrect length property on TextSelection.

The fix replaces selection.length with selection.end - selection.start to properly check the selection length, ensuring that single character formatting doesn't affect the toolbar state while maintaining the correct behavior for multiple character selections.

Related Issues

• Fix After formatText() modifies the style, the style is automatically turned on #2559

Type of Change

• Bug fix: Resolves an issue without altering current behavior.
• Tests: New or modified tests

Changes Made

• Modified toggle_style_button.dart to use correct TextSelection length calculation
• Added test cases to verify single character formatting behavior
• Added test utility class for testing

Testing

• Added unit tests that verify:
  • Single character formatting works without affecting toolbar state
  • Multiple character formatting works correctly with toolbar state changes
• All tests are passing