Add code coverage for DataGridViewDesigner (#13014)

Related #10773

## Proposed changes
Add unit test file: DataGridViewDesignerTests.cs for public methods of
the DataGridViewDesigner.cs, except for OnAddColumn and OnEditColumns
methods.

Author: Zheng-Li01

src/System.Windows.Forms.Design/tests/UnitTests/System/Windows/Forms/Design/DataGridViewDesignerTests.cs

@@ -0,0 +1,156 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.ComponentModel;
+using System.ComponentModel.Design;
+using Moq;
+
+namespace System.Windows.Forms.Design.Tests;
+
+public class DataGridViewDesignerTests : IDisposable
+{
+    private readonly DataGridViewDesigner _designer;
+    private readonly DataGridView _dataGridView;
+
+    public DataGridViewDesignerTests()
+    {
+        _designer = new();
+        _dataGridView = new();
+        _designer.Initialize(_dataGridView);
+    }
+
+    public void Dispose()
+    {
+        _designer.Dispose();
+        _dataGridView.Dispose();
+    }
+
+    [Fact]
+    public void Control_ReturnsDataGridView()
+    {
+        _designer.Control.Should().NotBeNull();
+        _designer.Control.Should().BeOfType<DataGridView>();
+    }
+
+    [Fact]
+    public void Constructor_SetsAutoResizeHandlesToTrue() =>
+        _designer.AutoResizeHandles.Should().BeTrue();
+
+    [Fact]
+    public void AssociatedComponents_ReturnsDataGridViewColumns() =>
+        _designer.AssociatedComponents.Should().BeSameAs(_dataGridView.Columns);
+
+    [Fact]
+    public void AutoSizeColumnsMode_Get_ReturnsExpected()
+    {
+        _dataGridView.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;
+        _designer.AutoSizeColumnsMode.Should().Be(DataGridViewAutoSizeColumnsMode.Fill);
+    }
+
+    [Fact]
+    public void AutoSizeColumnsMode_Set_CallsComponentChangeService()
+    {
+        Mock<IComponentChangeService> mockChangeService = new();
+        Mock<ISite> site = new();
+        site.Setup(s => s.GetService(typeof(IComponentChangeService))).Returns(mockChangeService.Object);
+        _dataGridView.Site = site.Object;
+
+        _designer.AutoSizeColumnsMode = DataGridViewAutoSizeColumnsMode.Fill;
+
+        mockChangeService.Verify(
+            s => s.OnComponentChanging(
+                It.IsAny<object>(),
+                It.IsAny<PropertyDescriptor>()
+            ),
+            Times.Exactly(_dataGridView.Columns.Count)
+        );
+
+        mockChangeService.Verify(
+            s => s.OnComponentChanged(
+                It.IsAny<object>(),
+                It.IsAny<PropertyDescriptor>(),
+                It.IsAny<object>(),
+                It.IsAny<object>()
+            ),
+            Times.Exactly(_dataGridView.Columns.Count)
+        );
+
+        _dataGridView.AutoSizeColumnsMode.Should().Be(DataGridViewAutoSizeColumnsMode.Fill);
+    }
+
+    [Fact]
+    public void DataSource_Get_ReturnsExpected()
+    {
+        object dataSource = new();
+        _dataGridView.DataSource = dataSource;
+
+        _designer.DataSource.Should().BeSameAs(dataSource);
+    }
+
+    [Fact]
+    public void DataSource_Set_SetsExpected()
+    {
+        object dataSource = new();
+        _designer.DataSource = dataSource;
+
+        _dataGridView.DataSource.Should().BeSameAs(dataSource);
+        _dataGridView.AutoGenerateColumns.Should().BeFalse();
+    }
+
+    [Fact]
+    public void DataSource_Set_Null_SetsExpected()
+    {
+        _dataGridView.AutoGenerateColumns = false;
+        _designer.DataSource = null;
+
+        _dataGridView.DataSource.Should().BeNull();
+        _dataGridView.AutoGenerateColumns.Should().BeFalse();
+    }
+
+    [Fact]
+    public void Initialize_SetsAutoGenerateColumnsCorrectly() =>
+        _dataGridView.AutoGenerateColumns.Should().BeTrue();
+
+    [Fact]
+    public void InitializeNewComponent_SetsColumnHeadersHeightSizeModeToAutoSize()
+    {
+        _designer.InitializeNewComponent(null);
+
+        _dataGridView.ColumnHeadersHeightSizeMode.Should().Be(DataGridViewColumnHeadersHeightSizeMode.AutoSize);
+    }
+
+    [Fact]
+    public void Verbs_ReturnsExpected()
+    {
+        DesignerVerbCollection verbs = _designer.Verbs;
+
+        verbs.Should().NotBeNull();
+        verbs.Count.Should().Be(2);
+        verbs[0]!.Text.Should().Be(SR.DataGridViewEditColumnsVerb);
+        verbs[1]!.Text.Should().Be(SR.DataGridViewAddColumnVerb);
+    }
+
+    [Fact]
+    public void ActionLists_CachesActionLists()
+    {
+        DesignerActionListCollection actionLists1 = _designer.ActionLists;
+        DesignerActionListCollection actionLists2 = _designer.ActionLists;
+
+        actionLists1.Should().BeSameAs(actionLists2);
+    }
+
+    [Fact]
+    public void PreFilterProperties_ShadowsPropertiesCorrectly()
+    {
+        Dictionary<string, PropertyDescriptor> properties = new()
+        {
+            { "AutoSizeColumnsMode", TypeDescriptor.GetProperties(typeof(DataGridView))["AutoSizeColumnsMode"]!},
+            { "DataSource", TypeDescriptor.GetProperties(typeof(DataGridView))["DataSource"]!}
+        };
+
+        _designer.TestAccessor().Dynamic.PreFilterProperties(properties);
+
+        properties["AutoSizeColumnsMode"].ComponentType.Should().Be(typeof(DataGridViewDesigner));
+        properties["DataSource"].ComponentType.Should().Be(typeof(DataGridViewDesigner));
+    }
+}