Add code coverage for DataGridViewComboBoxCell (#13654)

* Add code coverage for DataGridViewComboBoxCell

* Address FeedBacks

Author: Zheng-Li01

src/test/unit/System.Windows.Forms/System/Windows/Forms/DataGridViewComboBoxCellTests.cs

@@ -0,0 +1,358 @@
+// 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.Drawing;
+
+namespace System.Windows.Forms.Tests;
+
+public class DataGridViewComboBoxCellTests : IDisposable
+{
+    private readonly DataGridViewComboBoxCell _dataGridViewComboBoxCell;
+
+    public void Dispose() => _dataGridViewComboBoxCell.Dispose();
+
+    public DataGridViewComboBoxCellTests() =>
+        _dataGridViewComboBoxCell = new();
+
+    [Fact]
+    public void AutoComplete_DefaultValue_IsTrue() =>
+        _dataGridViewComboBoxCell.AutoComplete.Should().BeTrue();
+
+    [Fact]
+    public void AutoComplete_SetFalse_ChangesValue()
+    {
+        _dataGridViewComboBoxCell.AutoComplete = false;
+        _dataGridViewComboBoxCell.AutoComplete.Should().BeFalse();
+    }
+
+    [WinFormsFact]
+    public void DataSource_DefaultValue_IsNull() =>
+        _dataGridViewComboBoxCell.DataSource.Should().BeNull();
+
+    [WinFormsFact]
+    public void DataSource_SetToIList_StoresReference()
+    {
+        IList<string> list = ["a", "b"];
+        _dataGridViewComboBoxCell.DataSource = list;
+        _dataGridViewComboBoxCell.DataSource.Should().BeSameAs(list);
+    }
+
+    [WinFormsFact]
+    public void DataSource_SetToIListSource_StoresReference()
+    {
+        using BindingSource bindingSource = new();
+        _dataGridViewComboBoxCell.DataSource = bindingSource;
+
+        _dataGridViewComboBoxCell.DataSource.Should().BeSameAs(bindingSource);
+    }
+
+    [WinFormsFact]
+    public void DataSource_SetToInvalidType_Throws()
+    {
+        Exception? invalidDataSourceException = Record.Exception(() => _dataGridViewComboBoxCell.DataSource = 123);
+
+        invalidDataSourceException.Should().BeOfType<ArgumentException>();
+    }
+
+    [WinFormsFact]
+    public void DataSource_SetToNull_ClearsDisplayAndValueMember()
+    {
+        _dataGridViewComboBoxCell.DataSource = new List<string> { "a" };
+        _dataGridViewComboBoxCell.DisplayMember = "Name";
+        _dataGridViewComboBoxCell.ValueMember = "Id";
+        _dataGridViewComboBoxCell.DataSource = null;
+
+        _dataGridViewComboBoxCell.DataSource.Should().BeNull();
+        _dataGridViewComboBoxCell.DisplayMember.Should().BeEmpty();
+        _dataGridViewComboBoxCell.ValueMember.Should().BeEmpty();
+    }
+
+    [WinFormsFact]
+    public void DisplayStyleForCurrentCellOnly_DefaultValue_IsFalse() =>
+        _dataGridViewComboBoxCell.DisplayStyleForCurrentCellOnly.Should().BeFalse();
+
+    [Fact]
+    public void DropDownWidth_DefaultValue_IsOne() =>
+        _dataGridViewComboBoxCell.DropDownWidth.Should().Be(1);
+
+    [Theory]
+    [InlineData(5)]
+    [InlineData(100)]
+    public void DropDownWidth_SetValidValue_ChangesValue(int width)
+    {
+        _dataGridViewComboBoxCell.DropDownWidth = width;
+        _dataGridViewComboBoxCell.DropDownWidth.Should().Be(width);
+    }
+
+    [Theory]
+    [InlineData(0)]
+    [InlineData(-5)]
+    public void DropDownWidth_SetInvalidValue_Throws(int width)
+    {
+        Exception? dropDownWidthOutOfRangeException = Record.Exception(() => _dataGridViewComboBoxCell.DropDownWidth = width);
+
+        dropDownWidthOutOfRangeException.Should().BeOfType<ArgumentOutOfRangeException>();
+    }
+
+    [Fact]
+    public void FlatStyle_DefaultValue_IsStandard() =>
+        _dataGridViewComboBoxCell.FlatStyle.Should().Be(FlatStyle.Standard);
+
+    [WinFormsTheory]
+    [InlineData(FlatStyle.Flat)]
+    [InlineData(FlatStyle.Popup)]
+    [InlineData(FlatStyle.System)]
+    [InlineData(FlatStyle.Standard)]
+    public void FlatStyle_SetValidValue_ChangesValue(FlatStyle style)
+    {
+        _dataGridViewComboBoxCell.FlatStyle = style;
+        _dataGridViewComboBoxCell.FlatStyle.Should().Be(style);
+    }
+
+    [Fact]
+    public void MaxDropDownItems_DefaultValue_IsEight() =>
+        _dataGridViewComboBoxCell.MaxDropDownItems.Should().Be(DataGridViewComboBoxCell.DefaultMaxDropDownItems);
+
+    [Theory]
+    [InlineData(1)]
+    [InlineData(50)]
+    [InlineData(100)]
+    public void MaxDropDownItems_SetValidValue_ChangesValue(int value)
+    {
+        _dataGridViewComboBoxCell.MaxDropDownItems = value;
+        _dataGridViewComboBoxCell.MaxDropDownItems.Should().Be(value);
+    }
+
+    [Theory]
+    [InlineData(0)]
+    [InlineData(-1)]
+    [InlineData(101)]
+    [InlineData(200)]
+    public void MaxDropDownItems_SetInvalidValue_Throws(int value)
+    {
+        Exception? maxDropDownItemsOutOfRangeException = Record.Exception(() => _dataGridViewComboBoxCell.MaxDropDownItems = value);
+
+        maxDropDownItemsOutOfRangeException.Should().BeOfType<ArgumentOutOfRangeException>();
+    }
+
+    [Fact]
+    public void Sorted_DefaultValue_IsFalse() =>
+        _dataGridViewComboBoxCell.Sorted.Should().BeFalse();
+
+    [Fact]
+    public void Sorted_SetTrue_WithoutDataSource_SetsFlag()
+    {
+        _dataGridViewComboBoxCell.Sorted = true;
+        _dataGridViewComboBoxCell.Sorted.Should().BeTrue();
+    }
+
+    [WinFormsFact]
+    public void Sorted_SetTrue_WithDataSource_Throws()
+    {
+        _dataGridViewComboBoxCell.DataSource = new List<string> { "a", "b" };
+
+        Exception? sortedWithDataSourceException = Record.Exception(() => _dataGridViewComboBoxCell.Sorted = true);
+
+        sortedWithDataSourceException.Should().BeOfType<ArgumentException>();
+    }
+
+    [Fact]
+    public void ValueMember_DefaultValue_IsEmpty() =>
+        _dataGridViewComboBoxCell.ValueMember.Should().BeEmpty();
+
+    [WinFormsTheory]
+    [InlineData("Id")]
+    [InlineData("Name")]
+    [InlineData("")]
+    public void ValueMember_SetValue_ChangesValue(string value)
+    {
+        _dataGridViewComboBoxCell.ValueMember = value;
+        _dataGridViewComboBoxCell.ValueMember.Should().Be(value);
+    }
+
+    [Fact]
+    public void ValueType_DefaultValue_IsObject() =>
+        _dataGridViewComboBoxCell.ValueType.Should().Be(typeof(object));
+
+    private class StubPropertyDescriptor : PropertyDescriptor
+    {
+        private readonly Type _propertyType;
+
+        public StubPropertyDescriptor(string name, Type propertyType)
+            : base(name, null)
+        {
+            _propertyType = propertyType;
+        }
+
+        public override Type PropertyType => _propertyType;
+        public override void SetValue(object? component, object? value) { }
+        public override object? GetValue(object? component) => null!;
+        public override bool CanResetValue(object? component) => false;
+        public override void ResetValue(object? component) { }
+        public override bool IsReadOnly => true;
+        public override Type ComponentType => typeof(object);
+        public override bool ShouldSerializeValue(object? component) => false;
+    }
+
+    [Fact]
+    public void ValueType_WithDisplayMemberProperty_ReturnsPropertyType()
+    {
+        StubPropertyDescriptor prop = new("Name", typeof(string));
+
+        _dataGridViewComboBoxCell.TestAccessor().Dynamic.DisplayMemberProperty = prop;
+        _dataGridViewComboBoxCell.TestAccessor().Dynamic.ValueMemberProperty = null;
+
+        _dataGridViewComboBoxCell.ValueType.Should().Be(typeof(string));
+    }
+
+    [Fact]
+    public void GetContentBounds_ReturnsEmpty_WhenDataGridViewIsNull()
+    {
+        using Bitmap bmp = new(10, 10);
+        using Graphics g = Graphics.FromImage(bmp);
+        DataGridViewCellStyle style = new();
+
+        Rectangle result = _dataGridViewComboBoxCell.TestAccessor().Dynamic.GetContentBounds(g, style, 0);
+
+        result.Should().Be(Rectangle.Empty);
+    }
+
+    [Fact]
+    public void GetContentBounds_ReturnsEmpty_WhenRowIndexIsNegative()
+    {
+        using DataGridView dataGridView = new();
+        using DataGridViewComboBoxColumn column = new() { CellTemplate = _dataGridViewComboBoxCell };
+        dataGridView.Columns.Add(column);
+        using Bitmap bmp = new(10, 10);
+        using Graphics g = Graphics.FromImage(bmp);
+        DataGridViewCellStyle style = new();
+
+        Rectangle result = _dataGridViewComboBoxCell.TestAccessor().Dynamic.GetContentBounds(g, style, -1);
+
+        result.Should().Be(Rectangle.Empty);
+    }
+
+    [Fact]
+    public void GetErrorIconBounds_ReturnsEmpty_WhenDataGridViewIsNull()
+    {
+        using Bitmap bmp = new(10, 10);
+        using Graphics g = Graphics.FromImage(bmp);
+        DataGridViewCellStyle style = new();
+
+        Rectangle result = _dataGridViewComboBoxCell.TestAccessor().Dynamic.GetErrorIconBounds(g, style, 0);
+
+        result.Should().Be(Rectangle.Empty);
+    }
+
+    [Fact]
+    public void GetErrorIconBounds_UsingTestAccessor_ReturnsEmpty_WhenRowIndexIsNegative()
+    {
+        using DataGridView dataGridView = new();
+        using DataGridViewComboBoxColumn column = new() { CellTemplate = _dataGridViewComboBoxCell };
+        dataGridView.Columns.Add(column);
+        using Bitmap bmp = new(10, 10);
+        using Graphics g = Graphics.FromImage(bmp);
+        DataGridViewCellStyle style = new();
+
+        Rectangle result = _dataGridViewComboBoxCell.TestAccessor().Dynamic.GetErrorIconBounds(g, style, -1);
+
+        result.Should().Be(Rectangle.Empty);
+    }
+
+    [Fact]
+    public void GetPreferredSize_ReturnsMinusOne_WhenDataGridViewIsNull()
+    {
+        using Bitmap bmp = new(10, 10);
+        using Graphics g = Graphics.FromImage(bmp);
+        DataGridViewCellStyle style = new();
+
+        Size result = _dataGridViewComboBoxCell.TestAccessor().Dynamic.GetPreferredSize(
+            g,
+            style,
+            0,
+            new Size(100, 20));
+
+        result.Should().Be(new Size(-1, -1));
+    }
+
+    [Theory]
+    [InlineData(Keys.A, false, false, false, true)]
+    [InlineData(Keys.F4, false, false, false, true)]
+    [InlineData(Keys.Space, false, false, false, true)]
+    [InlineData(Keys.Space, true, false, false, false)]
+    [InlineData(Keys.Down, false, true, false, true)]
+    [InlineData(Keys.Up, false, true, false, true)]
+    [InlineData(Keys.Down, false, false, false, false)]
+    [InlineData(Keys.F1, false, false, false, false)]
+    [InlineData(Keys.F24, false, false, false, false)]
+    [InlineData(Keys.A, false, false, true, false)]
+    public void KeyEntersEditMode_ReturnsExpected(Keys key, bool shift, bool alt, bool control, bool expected)
+    {
+        Keys keyData = key;
+        if (shift)
+        {
+            keyData |= Keys.Shift;
+        }
+
+        if (alt)
+        {
+            keyData |= Keys.Alt;
+        }
+
+        if (control)
+        {
+            keyData |= Keys.Control;
+        }
+
+        KeyEventArgs e = new(keyData);
+        bool result = _dataGridViewComboBoxCell.KeyEntersEditMode(e);
+        result.Should().Be(expected);
+    }
+
+    [Fact]
+    public void ParseFormattedValue_UsesValueTypeConverter_WhenValueTypeConverterIsProvided()
+    {
+        using DataGridView dataGridView = new();
+        using DataGridViewComboBoxColumn column = new() { CellTemplate = _dataGridViewComboBoxCell };
+        dataGridView.Columns.Add(column);
+        DataGridViewCellStyle style = new();
+
+        object? result = _dataGridViewComboBoxCell.ParseFormattedValue(
+            "test",
+            style,
+            null,
+            TypeDescriptor.GetConverter(typeof(string)));
+
+        result.Should().Be("test");
+    }
+
+    [Fact]
+    public void ParseFormattedValue_UsesValueMemberPropertyConverter_WhenValueTypeConverterIsNull()
+    {
+        using DataGridView dataGridView = new();
+        using DataGridViewComboBoxColumn column = new() { CellTemplate = _dataGridViewComboBoxCell };
+        dataGridView.Columns.Add(column);
+        DataGridViewCellStyle style = new();
+
+        StubPropertyDescriptor prop = new("Id", typeof(string));
+        _dataGridViewComboBoxCell.TestAccessor().Dynamic.ValueMemberProperty = prop;
+
+        object? result = _dataGridViewComboBoxCell.ParseFormattedValue("abc", style, null, null);
+
+        result.Should().Be("abc");
+    }
+
+    [Fact]
+    public void ParseFormattedValue_UsesParseFormattedValueInternal_WithValueType_WhenNoDataManagerOrMembers()
+    {
+        using DataGridView dataGridView = new();
+        using DataGridViewComboBoxColumn column = new() { CellTemplate = _dataGridViewComboBoxCell };
+        dataGridView.Columns.Add(column);
+        DataGridViewCellStyle style = new();
+
+        object? result = _dataGridViewComboBoxCell.ParseFormattedValue("test", style, null, null);
+
+        result.Should().Be("test");
+    }
+}