Add conformance tests for multi-column layout with semantic validation

Source/QuestPDF.ConformanceTests/MultiColumnTests.cs

@@ -0,0 +1,67 @@
+using QuestPDF.ConformanceTests.TestEngine;
+using QuestPDF.Drawing;
+using QuestPDF.Fluent;
+using QuestPDF.Helpers;
+
+namespace QuestPDF.ConformanceTests;
+
+internal class MultiColumnTests : ConformanceTestBase
+{
+    protected override Document GetDocumentUnderTest()
+    {
+        return Document
+            .Create(document =>
+            {
+                document.Page(page =>
+                {
+                    page.Margin(60);
+
+                    page.Content()
+                        .MultiColumn(multiColumn =>
+                        {
+                            multiColumn.Spacing(75);
+                            
+                            multiColumn
+                                .Spacer()
+                                .PaddingHorizontal(25)
+                                .Background(Colors.Blue.Lighten4)
+                                .RotateLeft()
+                                .AlignMiddle()
+                                .AlignCenter()
+                                .Text("This text should not be a part of the semantic tree")
+                                .FontColor(Colors.Blue.Darken4)
+                                .Bold();
+                                
+                            multiColumn
+                                .Content()
+                                .Column(column =>
+                                {
+                                    column.Spacing(25);
+                                    
+                                    foreach (var i in Enumerable.Range(1, 25))
+                                    {
+                                        column.Item()
+                                            .AlignCenter()
+                                            .Background(Colors.Grey.Lighten3)
+                                            .Padding(10)
+                                            .Text(text =>
+                                            {
+                                                text.Span($"Chapter {i}: ").Bold();
+                                                text.Span(Placeholders.LoremIpsum());
+                                            });
+                                    }
+                                });
+                        });
+                });
+            });
+    }
+    
+    protected override SemanticTreeNode? GetExpectedSemanticTree()
+    {
+        return ExpectedSemanticTree.DocumentRoot(root =>
+        {
+            foreach (var i in Enumerable.Range(1, 25))
+                root.Child("P");
+        });
+    }
+}