Add code coverage for ButtonPopupAdapter (#13731)

* Add code coverage for ButtonPopupAdapter

* Address FeedBacks

Author: Zheng-Li01

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

@@ -0,0 +1,144 @@
+// Licensed to the .NET Foundation under one or more agreements.
+// The .NET Foundation licenses this file to you under the MIT license.
+
+using System.Drawing;
+using System.Windows.Forms.ButtonInternal;
+using static System.Windows.Forms.ButtonInternal.ButtonBaseAdapter;
+
+namespace System.Windows.Forms.Tests;
+
+public class ButtonPopupAdapterTests : IDisposable
+{
+    public ButtonBase button { get; }
+    internal ButtonPopupAdapter adapter { get; }
+
+    public ButtonPopupAdapterTests()
+    {
+        button = new TestButtonBase();
+        adapter = new(button);
+    }
+
+    public void Dispose() => button.Dispose();
+
+    public static TheoryData<CheckState> PaintStates => new()
+    {
+        CheckState.Unchecked,
+        CheckState.Checked,
+        CheckState.Indeterminate
+    };
+
+    private class TestButtonBase : ButtonBase
+    {
+        public bool IsDefaultSet { get; set; }
+        public Rectangle ClientRectangleValue { get; set; } = new(0, 0, 100, 30);
+
+        internal override Rectangle OverChangeRectangle => ClientRectangleValue;
+
+        internal override ButtonBaseAdapter CreateStandardAdapter() => new ButtonPopupAdapter(this);
+
+        internal override StringFormat CreateStringFormat() => new StringFormat();
+
+        internal override TextFormatFlags CreateTextFormatFlags() => TextFormatFlags.Default;
+    }
+
+    [WinFormsTheory]
+    [MemberData(nameof(PaintStates))]
+    public void PaintUp_DoesNotThrow(CheckState state)
+    {
+        using Bitmap bitmap = new(100, 30);
+        using Graphics graphics = Graphics.FromImage(bitmap);
+        PaintEventArgs e = new(graphics, new Rectangle(0, 0, 100, 30));
+
+        Exception? exception = Record.Exception(() => adapter.PaintUp(e, state));
+
+        exception.Should().BeNull();
+    }
+
+    [WinFormsTheory]
+    [MemberData(nameof(PaintStates))]
+    public void PaintOver_DoesNotThrow(CheckState state)
+    {
+        using Bitmap bitmap = new(100, 30);
+        using Graphics graphics = Graphics.FromImage(bitmap);
+        PaintEventArgs e = new(graphics, new Rectangle(0, 0, 100, 30));
+
+        Exception? exception = Record.Exception(() => adapter.PaintOver(e, state));
+
+        exception.Should().BeNull();
+    }
+
+    [WinFormsTheory]
+    [MemberData(nameof(PaintStates))]
+    public void PaintDown_DoesNotThrow(CheckState state)
+    {
+        using Bitmap bitmap = new(100, 30);
+        using Graphics graphics = Graphics.FromImage(bitmap);
+        PaintEventArgs e = new(graphics, new Rectangle(0, 0, 100, 30));
+
+        Exception? exception = Record.Exception(() => adapter.PaintDown(e, state));
+
+        exception.Should().BeNull();
+    }
+
+    [Fact]
+    public void PaintPopupLayout_ReturnsLayoutOptions_WithExpectedBorderAndPadding()
+    {
+        Rectangle clientRectangle = new(0, 0, 100, 30);
+        Padding padding = new(2);
+        bool isDefault = false;
+        using Font font = SystemFonts.DefaultFont;
+        string text = "Test";
+        bool enabled = true;
+        ContentAlignment textAlign = ContentAlignment.MiddleCenter;
+        RightToLeft rightToLeft = RightToLeft.No;
+
+        LayoutOptions layoutOptions = ButtonPopupAdapter.PaintPopupLayout(
+            up: true,
+            paintedBorder: 1,
+            clientRectangle,
+            padding,
+            isDefault,
+            font,
+            text,
+            enabled,
+            textAlign,
+            rightToLeft);
+
+        layoutOptions.BorderSize.Should().Be(1);
+        layoutOptions.PaddingSize.Should().Be(1);
+        layoutOptions.HintTextUp.Should().BeFalse();
+        layoutOptions.TextOffset.Should().BeFalse();
+        layoutOptions.ShadowedText.Should().Be(SystemInformation.HighContrast);
+    }
+
+    [Theory]
+    [InlineData(true, 0)]
+    [InlineData(false, 2)]
+    public void PaintPopupLayout_BorderAndPaddingSumIsTwo(bool up, int paintedBorder)
+    {
+        Rectangle clientRectangle = new(0, 0, 100, 30);
+        Padding padding = new(0);
+        bool isDefault = false;
+        using Font font = SystemFonts.DefaultFont;
+        string text = string.Empty;
+        bool enabled = false;
+        ContentAlignment textAlign = ContentAlignment.TopLeft;
+        RightToLeft rightToLeft = RightToLeft.No;
+
+        LayoutOptions layoutOptions = ButtonPopupAdapter.PaintPopupLayout(
+            up,
+            paintedBorder,
+            clientRectangle,
+            padding,
+            isDefault,
+            font,
+            text,
+            enabled,
+            textAlign,
+            rightToLeft);
+
+        int sum = layoutOptions.BorderSize + layoutOptions.PaddingSize;
+
+        sum.Should().Be(2);
+    }
+}