fix: title empty if AddSegment is not called

src/OrchardCore/OrchardCore.DisplayManagement/Title/PageTitleBuilder.cs

@@ -1,3 +1,4 @@
+using System;
 using System.Collections.Generic;
 using Microsoft.AspNetCore.Html;
 using OrchardCore.DisplayManagement.Zones;
@@ -9,7 +10,7 @@ public class PageTitleBuilder : IPageTitleBuilder
         private readonly static HtmlString _defaultTitleSeparator = new(" - ");
 
         private readonly List<PositionalTitlePart> _titleParts;
-        private IHtmlContent _title;
+        private HtmlContentBuilder _title;
         private IHtmlContent _fixedTitle;
 
         public PageTitleBuilder()
@@ -48,7 +49,7 @@ public IHtmlContent GenerateTitle(IHtmlContent separator)
                 return _fixedTitle;
             }
 
-            if (_title != null)
+            if (_title is { Count: > 0 })
             {
                 return _title;
             }
@@ -57,13 +58,14 @@ public IHtmlContent GenerateTitle(IHtmlContent separator)
 
             _titleParts.Sort(FlatPositionComparer.Instance);
 
-            var htmlContentBuilder = new HtmlContentBuilder();
-
             if (_titleParts.Count == 0)
             {
                 return HtmlString.Empty;
             }
 
+            // _titleParts.Count * 2 because we add a separator for each entry
+            var htmlContentBuilder = new HtmlContentBuilder(_titleParts.Count * 2);
+
             for (var i = 0; i < _titleParts.Count; i++)
             {
                 htmlContentBuilder.AppendHtml(_titleParts[i].Value);
@@ -82,6 +84,7 @@ public IHtmlContent GenerateTitle(IHtmlContent separator)
         public void Clear()
         {
             _fixedTitle = null;
+            _title = null;
             _titleParts.Clear();
         }
     }

test/OrchardCore.Tests/DisplayManagement/Title/PageTitleBuilderTests.cs

@@ -0,0 +1,149 @@
+using Cysharp.Text;
+
+namespace OrchardCore.DisplayManagement.Title
+{
+    public class PageTitleBuilderTests
+    {
+        private const string Separator = " - ";
+        private const string SimpleTitle = "I'm a title";
+        private const string FirstPartTitle = "first part";
+        private const string SecondPartTitle = "second part";
+
+        private readonly IServiceProvider _serviceProvider;
+
+        public PageTitleBuilderTests()
+        {
+            var serviceCollection = new ServiceCollection();
+            serviceCollection.AddScoped<IPageTitleBuilder, PageTitleBuilder>();
+
+            _serviceProvider = serviceCollection.BuildServiceProvider();
+        }
+
+        [Fact]
+        public void GenerateTitleEmpty()
+        {
+            // Arrange
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+
+            // Act & Assert
+            Assert.Equal(string.Empty, ToString(pageTitleBuilder.GenerateTitle()));
+        }
+
+        [Fact]
+        public void FixedTitleSet()
+        {
+            // Arrange
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.SetFixedTitle(new HtmlString(SimpleTitle));
+
+            // Act & Assert
+            Assert.Equal(SimpleTitle, ToString(pageTitleBuilder.GenerateTitle()));
+        }
+
+        [Fact]
+        public void FixedTitleClearAndCheck()
+        {
+            // Arrange
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.SetFixedTitle(new HtmlString(SimpleTitle));
+            pageTitleBuilder.Clear();
+
+            // Act & Assert
+            Assert.Equal(string.Empty, ToString(pageTitleBuilder.GenerateTitle()));
+        }
+
+        [Fact]
+        public void FixedTitleAddSegment()
+        {
+            // Arrange
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.SetFixedTitle(new HtmlString(SimpleTitle));
+
+            // Act & Assert
+            pageTitleBuilder.AddSegment(new HtmlString("you don't see me"));
+            Assert.Equal(SimpleTitle, ToString(pageTitleBuilder.GenerateTitle()));
+        }
+
+        [Fact]
+        public void TitleAddSegment()
+        {
+            // Arrange
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            // Act & Assert
+            pageTitleBuilder.AddSegment(new HtmlString(SimpleTitle), "after");
+            Assert.Equal(SimpleTitle, ToString(pageTitleBuilder.GenerateTitle()));
+        }
+
+        [Fact]
+        public void TitleMultiAddSegment()
+        {
+            // Arrange
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            // Act & Assert
+            pageTitleBuilder.AddSegment(new HtmlString(FirstPartTitle), "after");
+            Assert.Equal(FirstPartTitle, ToString(pageTitleBuilder.GenerateTitle(new HtmlString(Separator))));
+            pageTitleBuilder.AddSegment(new HtmlString(SecondPartTitle), "after");
+            Assert.Equal($"{FirstPartTitle}{Separator}{SecondPartTitle}", ToString(pageTitleBuilder.GenerateTitle(new HtmlString(Separator))));
+        }
+
+        [Fact]
+        public void TitleAddAndClear()
+        {
+            // Arrange
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            // Act & Assert
+            pageTitleBuilder.AddSegment(new HtmlString(FirstPartTitle), "after");
+            Assert.Equal(FirstPartTitle, ToString(pageTitleBuilder.GenerateTitle(new HtmlString(Separator))));
+            pageTitleBuilder.Clear();
+            Assert.Equal(string.Empty, ToString(pageTitleBuilder.GenerateTitle(new HtmlString(Separator))));
+        }
+
+        [Fact]
+        public void TitleMultiGenerateTitle()
+        {
+            // Arrange
+            var pageTitleBuilder = _serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            // Act
+            pageTitleBuilder.AddSegment(new HtmlString(FirstPartTitle), "after");
+
+            // Assert
+            Assert.Equal(FirstPartTitle, ToString(pageTitleBuilder.GenerateTitle(new HtmlString(Separator))));
+            Assert.Equal(FirstPartTitle, ToString(pageTitleBuilder.GenerateTitle(new HtmlString(Separator))));
+        }
+
+        [Fact]
+        public void TitleAddSegments()
+        {
+            // Arrange
+            var pageTitleBuilder = (PageTitleBuilder)_serviceProvider.GetService<IPageTitleBuilder>();
+            pageTitleBuilder.Clear();
+
+            var elements = new IHtmlContent[]
+            {
+                new HtmlString(FirstPartTitle),
+                new HtmlString(SecondPartTitle)
+            };
+
+            pageTitleBuilder.AddSegments(elements, "after");
+
+            // Act & Assert
+            Assert.Equal($"{FirstPartTitle}{Separator}{SecondPartTitle}", ToString(pageTitleBuilder.GenerateTitle(new HtmlString(Separator))));
+        }
+
+        private static string ToString(IHtmlContent content)
+        {
+            using var writer = new ZStringWriter();
+            content.WriteTo(writer, HtmlEncoder.Default);
+
+            return writer.ToString();
+        }
+    }
+}