Add code coverage for DataGridViewColumnTypePicker

[Zheng-Li01]

Related #10773

Proposed changes

Add unit test file: DataGridViewColumnTypePicker.cs for public methods of the DataGridViewColumnTypePicker.cs

Microsoft Reviewers: Open in CodeFlow

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 61.08310%. Comparing base (61a4f2a) to head (9975f82).
Report is 26 commits behind head on main.

Additional details and impacted files

@@                 Coverage Diff                  @@
##                main      #13055          +/-   ##
====================================================
- Coverage   76.10018%   61.08310%   -15.01708%     
====================================================
  Files           3275        1540        -1735     
  Lines         643804      158083      -485721     
  Branches       47445       14727       -32718     
====================================================
- Hits          489936       96562      -393374     
+ Misses        150301       60827       -89474     
+ Partials        3567         694        -2873     

Flag	Coverage Δ
Debug	61.08310% <100.00000%> (-15.01708%)	⬇️
integration	10.73772% <ø> (-7.30089%)	⬇️
production	38.89160% <ø> (-11.23329%)	⬇️
test	95.67350% <100.00000%> (-1.27694%)	⬇️
unit	36.31426% <ø> (-11.24391%)	⬇️

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[Copilot]

PR Overview

This pull request adds unit tests for the DataGridViewColumnTypePicker class to improve code coverage.

• Introduces a new test file with various tests for control initialization, property setting, and event handling.
• Verifies that the picker initializes its ListBox correctly, sets visual properties, and handles type selection appropriately.

Reviewed Changes

File	Description
src/System.Windows.Forms.Design/tests/UnitTests/System/Windows/Forms/Design/DataGridViewColumnTypePickerTests.cs	New unit tests to validate the behavior of DataGridViewColumnTypePicker

Copilot reviewed 1 out of 1 changed files in this pull request and generated 2 comments.

[ricardobossan]

Thank you!