Add unit tests for LinkLabel

src/System.Windows.Forms/tests/UnitTests/LinkLabelTests.cs

@@ -1,6 +1,10 @@
 // Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+#nullable enable
+
+using System.Drawing;
+
 namespace System.Windows.Forms.Tests;
 
 public class LinkLabelTests
@@ -15,4 +19,289 @@ public void LinkLabel_Constructor()
         Assert.Equal(0, label.LinkArea.Start);
         Assert.Equal(0, label.LinkArea.Length);
     }
+
+    [WinFormsFact]
+    public void LinkLabel_FlatStyle_Get_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+        label.FlatStyle.Should().Be(FlatStyle.Standard);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_FlatStyle_Set_GetReturnsExpected()
+    {
+        using LinkLabel label = new();
+
+        SetAndVerifyFlatStyle(label, FlatStyle.Flat);
+        SetAndVerifyFlatStyle(label, FlatStyle.Popup);
+        SetAndVerifyFlatStyle(label, FlatStyle.System);
+    }
+
+    private static void SetAndVerifyFlatStyle(LinkLabel label, FlatStyle style)
+    {
+        label.FlatStyle = style;
+        label.FlatStyle.Should().Be(style);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkArea_Get_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+        label.LinkArea.Should().Be(new LinkArea(0, 0));
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkArea_Set_GetReturnsExpected()
+    {
+        using LinkLabel label = new();
+
+        SetAndVerifyLinkArea(label, new LinkArea(1, 2));
+        SetAndVerifyLinkArea(label, new LinkArea(3, 4));
+    }
+
+    private static void SetAndVerifyLinkArea(LinkLabel label, LinkArea area)
+    {
+        label.LinkArea = area;
+        label.LinkArea.Should().Be(area);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkArea_SetNegativeStart_ThrowsArgumentOutOfRangeException()
+    {
+        using LinkLabel label = new();
+        Action act = () => label.LinkArea = new LinkArea(-1, 2);
+        act.Should().Throw<ArgumentOutOfRangeException>().WithMessage("*LinkArea*");
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkArea_SetNegativeLength_ThrowsArgumentOutOfRangeException()
+    {
+        using LinkLabel label = new();
+        Action act = () => label.LinkArea = new LinkArea(1, -2);
+        act.Should().Throw<ArgumentOutOfRangeException>().WithMessage("*LinkArea*");
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkArea_Set_UpdatesSelectability()
+    {
+        using LinkLabel label = new();
+        label.Text = "Text";
+
+        label.LinkArea = new LinkArea(1, 2);
+        label.TabStop.Should().BeTrue();
+
+        label.LinkArea = new LinkArea(0, 0);
+        label.TabStop.Should().BeFalse();
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkBehavior_Get_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+        label.LinkBehavior.Should().Be(LinkBehavior.SystemDefault);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkBehavior_Set_GetReturnsExpected()
+    {
+        using LinkLabel label = new();
+
+        SetAndVerifyLinkBehavior(label, LinkBehavior.AlwaysUnderline);
+        SetAndVerifyLinkBehavior(label, LinkBehavior.HoverUnderline);
+        SetAndVerifyLinkBehavior(label, LinkBehavior.NeverUnderline);
+    }
+
+    private static void SetAndVerifyLinkBehavior(LinkLabel label, LinkBehavior behavior)
+    {
+        label.LinkBehavior = behavior;
+        label.LinkBehavior.Should().Be(behavior);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkVisited_Get_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+        label.LinkVisited.Should().BeFalse();
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkVisited_Set_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+
+        SetAndVerifyLinkVisited(label, true);
+        SetAndVerifyLinkVisited(label, false);
+    }
+
+    private static void SetAndVerifyLinkVisited(LinkLabel label, bool visited)
+    {
+        label.LinkVisited = visited;
+        label.LinkVisited.Should().Be(visited);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkVisited_Set_AddsLinkIfNoneExists()
+    {
+        using LinkLabel label = new();
+        label.LinkVisited = true;
+        label.Links.Count.Should().Be(1);
+        label.Links[0].Visited.Should().BeTrue();
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkVisited_Set_UpdatesExistingLink()
+    {
+        using LinkLabel label = new();
+        label.Links.Add(new LinkLabel.Link(label) { Visited = false });
+
+        label.LinkVisited = true;
+        label.Links[0].Visited.Should().BeTrue();
+
+        label.LinkVisited = false;
+        label.Links[0].Visited.Should().BeFalse();
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_TabStop_Get_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+        label.TabStop.Should().BeFalse();
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_TabStop_Set_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+
+        SetAndVerifyTabStop(label, true);
+        SetAndVerifyTabStop(label, false);
+    }
+
+    private static void SetAndVerifyTabStop(LinkLabel label, bool tabStop)
+    {
+        label.TabStop = tabStop;
+        label.TabStop.Should().Be(tabStop);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_TabStop_Set_RaisesTabStopChangedEvent()
+    {
+        using LinkLabel label = new();
+        bool eventRaised = false;
+        label.TabStopChanged += (sender, e) => eventRaised = true;
+
+        label.TabStop = true;
+        eventRaised.Should().BeTrue();
+
+        eventRaised = false;
+        label.TabStop = false;
+        eventRaised.Should().BeTrue();
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_Padding_Get_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+        label.Padding.Should().Be(new Padding(0));
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_Padding_Set_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+
+        SetAndVerifyPadding(label, new Padding(1, 2, 3, 4));
+        SetAndVerifyPadding(label, new Padding(5));
+    }
+
+    private static void SetAndVerifyPadding(LinkLabel label, Padding padding)
+    {
+        label.Padding = padding;
+        label.Padding.Should().Be(padding);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_VisitedLinkColor_Get_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+        label.VisitedLinkColor.Should().Be(LinkUtilities.GetVisitedLinkColor());
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_VisitedLinkColor_Set_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+
+        SetAndVerifyVisitedLinkColor(label, Color.Red);
+        SetAndVerifyVisitedLinkColor(label, Color.Blue);
+    }
+
+    private static void SetAndVerifyVisitedLinkColor(LinkLabel label, Color color)
+    {
+        label.VisitedLinkColor = color;
+        label.VisitedLinkColor.Should().Be(color);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_VisitedLinkColor_Set_UpdatesLink()
+    {
+        using LinkLabel label = new();
+        label.Links.Add(new LinkLabel.Link(label) { Visited = true });
+        label.VisitedLinkColor = Color.Red;
+        label.VisitedLinkColor.Should().Be(Color.Red);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_LinkClicked_RaisesEvent()
+    {
+        using TestLinkLabel label = new();
+        bool eventRaised = false;
+        label.LinkClicked += (sender, e) => eventRaised = true;
+
+        var link = new LinkLabel.Link(label);
+        label.Links.Add(link);
+        label.OnLinkClicked(new LinkLabelLinkClickedEventArgs(link));
+
+        eventRaised.Should().BeTrue();
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_UseCompatibleTextRendering_Get_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+        label.UseCompatibleTextRendering.Should().BeTrue();
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_UseCompatibleTextRendering_Set_ReturnsExpected()
+    {
+        using LinkLabel label = new();
+
+        SetAndVerifyUseCompatibleTextRendering(label, true);
+        SetAndVerifyUseCompatibleTextRendering(label, false);
+    }
+
+    private static void SetAndVerifyUseCompatibleTextRendering(LinkLabel label, bool value)
+    {
+        label.UseCompatibleTextRendering = value;
+        label.UseCompatibleTextRendering.Should().Be(value);
+    }
+
+    [WinFormsFact]
+    public void LinkLabel_UseCompatibleTextRendering_Set_TriggersLayout()
+    {
+        using LinkLabel label = new();
+        bool layoutCalled = false;
+        label.Layout += (sender, e) => layoutCalled = true;
+
+        label.UseCompatibleTextRendering = true;
+        label.PerformLayout();
+
+        layoutCalled.Should().BeTrue();
+    }
+
+    private class TestLinkLabel : LinkLabel
+    {
+        public new void OnLinkClicked(LinkLabelLinkClickedEventArgs e) => base.OnLinkClicked(e);
+    }
 }