Add test coverage for TextBox

[Eudora-Li01]

Related ##10453

Proposed changes

• Add unit tests for TextBox to test its properties: AutoCompleteMode and AutoCompleteSource.
• Add renderer unit tests for TextBox to test its methods: DrawTestBox

Customer Impact

• None

Regression?

• No

Risk

• Minimal

Test methodology

• Unit tests

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 74.36411%. Comparing base (cef4d2a) to head (8e10713).
Report is 11 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                 @@
##                main      #11021         +/-   ##
===================================================
+ Coverage   73.47398%   74.36411%   +0.89012%     
===================================================
  Files           3101        3010         -91     
  Lines         632447      625073       -7374     
  Branches       46688       46502        -186     
===================================================
+ Hits          464684      464830        +146     
+ Misses        164355      156835       -7520     
  Partials        3408        3408                 

Flag	Coverage Δ
Debug	74.36411% <100.00000%> (+0.89012%)	⬆️
integration	18.36385% <ø> (ø)
production	46.98086% <ø> (+0.01729%)	⬆️
test	97.06625% <100.00000%> (+2.07797%)	⬆️
unit	43.95043% <ø> (+0.01764%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

[LeafShi1]

@lonitra Please help review this PR

[lonitra]

👍